If audio is determined to be deactivated via the audio source (via the
new "audio_activate" and "audio_deactivate" signals), hide the audio
source in the mixer.

Adds functions to allow sources to inform the UI whether the audio is
currently active or not.  Allows the ability to turn on/off the items in
the mixer.

It was determined that rerouting audio through OBS currently isn't the
best idea even with monitoring enabled, primarily due to the fact that
audio monitoring has never had this wide of testing before, and that
many users complained that they were not getting audio for (as of yet)
unknown reasons from audio monitoring.  It would appear that we need to
address the issues with audio monitoring first before attempting to use
audio monitoring with any sources by default.  For now, audio will
reroute through CEF by default, and then the user must explicitly use
the option "Control audio via OBS", (renamed from "reroute audio", and
now disabled by default), to enable browser audio control through OBS.

There are other issues that need to be resolved as well, and once all
the various issues are addressed, the setting default can be allowed to
change back.

This was actually the line of code that the mixer dock widget crash was
triggered by.  This technically shouldn't ever be null, but better to be
safe than sorry.

The function added to the BrowserDock class is SetWidget, not setWidget.

I realize now that using the same exact function name but with an
uppercase starting letter rather than a lowercase starting letter wasn't
smart.

This prevents VideoFormat::Any from unintentionally selecting H264 when
MJPEG is the only other format available.

This fixes a bug where certain devices (Logitech C920 with latest
drivers) will only have H264 and MJPEG available, and using
VideoFormat::Any will then select H264 over MJPEG because it's the first
format value and has the same priority as MJPEG.  So now, MJPEG will be
prioritized over H264 instead.

This did not get enough testing, so disable it for now until more
devices can be tested (especially the live gamer portable).

If for whatever reason the format is swapped between BGRA/BGRX in an
async filter, swap the texture to compensate for that.  This allows
plugins to change the format if necessary.

win-dshow: Fix color range when using FFmpeg decode

Fixes a bug where where if http://absolute/ are used directly by the
user, the local files used with it would not function correctly.

The extra browser panels would always create on startup due to the
visibility change.  This fixes that by ensuring that this call blocks
signals, and ensures that the call only happens on first creation by the
user and not when the user is loading on startup.

In the view -> Docks menu, when a user first creates a custom browser
dock, the menu item associated with them used to hide/show them will be
unchecked in the menu by mistake.  This ensures they're checked when
first created.

Full color range seems to be active when decoding video with FFMmpeg
even when partial is explicitly selected. This should keep the range
synchronized.

This reverts commit b5843caa.

This breaks some hotkeys because the signals are tied to a signal which
is now triggered because "toggled" is used instead of "clicked", so just
revert it for now for the release and look at it later post-patch.

Setting the check state cause the toggle signal to trigger, so it would
pause and immediately unpause.

Request contexts don't appear to work with relative paths, only absolute
paths.  This fixes the bug where when using portable mode,
cookies/session wouldn't save because obs_module_config_path() was
returning a relative path rather than an absolute path.

Fixes duplicate visibility notifications when using 3440.

Lookahead causes playback issues when bitrate changes mid-stream.
Bitrate can suddenly drop to 0, and other issues such as audio
stuttering on Twitch have been observed.  Turning off lookahead fixed
the issue.  Lookahead is normally off by default anyway.

Browser panels were having their initial visibility state always being
set to false.  This fixes that by only setting visibility state on
browser objects which explicitly call the visibility message (i.e. only
browser sources).

CI: Update CEF on osx to 3770

In newer CEF builds the http://absolute/ scheme handler factory seems to
never complete when accessing large media files due to an apparent bug
in the Chromium media player (XHR requests complete fine).  At the same
time, file:// URLs are working just fine.

file:// URLs will be used where available (CEF 3440+) falling back to
BrowserSchemeHandlerFactory on older CEF versions.

UI: Various screen reader fixes

This reverts commit 46c5780a.

This needs to be reverted for now because users who did not set a size
on it (left it at default and just stretched it) will now suddenly have
the source's size change out of nowhere.  There needs to be backward
compatibility implementation for this.

Reverts the container widget, then decouples the browser's window handle
from its parent instead.  This allows calling DestroyBrowser() safely.

Shuts down the actual browsers internally when the browser docks are
hidden by user.

Refactors all cases where a window class was created to show a browser
dock in to one class: BrowserDock.  Removes some unnecessary code
duplication.

This commit fixes various issues with screen readers in the main OBS
interface. These were tested using NVDA on Windows 10 1903.

Checkboxes or buttons which toggle, when receiving an activate signal
from the screen reader would visually update, but not perform any
action. This is because they're listening only for clicks. They should
all now be listening for toggles instead.

The screen reader would navigate through the UI in the order that
elements are defined in the .ui XML, and not by their row positions.
The XML has been reordered so that things should be defined in their row
order.

Audio track selection now says Track 1, 2, etc, rather than just the
number. Various checkboxes that just say "Enable" now have accessible
text that says what the enable is for (since it says "checkbox", the
fact it's an enable should hopefully be clear). Type in the recording
tab of output now has accessible text which says "Recording Type".

All the right side buttons in hotkeys now have tooltips, and by
extension, accessible text. Currently it does not yet say what hotkey
the action is in relation to, but that would require more locales.

Fix Variable type and format specifier

Allows the ability for users to use audio through CEF (previous
behavior) by unchecking the "Reroute audio through OBS" checkbox if they
so choose.

Using WasHidden() for the purposes of visibility no longer can be relied
upon due to some sort of bug with OSR in Chromium.  This issue does not
happen when using 3440.  The browser works fine without WasHidden()
calls, so we must remove its usage or be forced to use 3440.  For those
who need the visibility handling, an alternative will have to be used
once it's available.

Additionally, this reverts the failed workaround to use OBS FPS in place
of SignalBeginFrame() because that code is no longer needed due to the
WasHidden() removal.

libobs: Fix Area shaders missing for RGB output