UI: Fix vcam button not changing colors when checked

UI: Remove duplicate media timer code

This fixes the remaining bugs that were still present when trying to fix
audio-related crashes with AJA devices.

This fixes a bug with the Rachni theme in which the virtual
camera button wouldn't change colors when active.

The old version of the device toolbar was a complex situation.  Because
of the fact that device properties can take significant time to query,
this put an unpleasant burden on the UI thread; so to fix this problem,
the device toolbar was made to be threaded.  However, threading is a
complex and dangerous thing, and there is a fear that this could cause
complications down the line whenever users are simply selecting devices.

So for the time being, as a safety precaution, simplify the device
toolbar down to just the "activate" button, and make it so that if users
really need to query and change the devices, that they need to
explicitly open the properties.  That way the devices aren't being
queried constantly every time a device source is selected.

Alternatively in the future, device enumeration could be cached, but
seeing as that's a significant amount of work and needs to take in to
account whether a user adds/removes a device while the process is
active, that's not going to happen any time soon.

This removes duplicate code that is already in the
start/stop timer functions.

This isn't particularly needed, as a service with multiple tracks won't
be using multiple tracks to begin with anyway.  This might change later,
but for now just mark it deprecated.

Unify color space settings as 709

Fixes an issue where when paused, the thread loop would continue to
repeat endlessly until unpaused.

UI: Fix studio mode load bug

UI: Ensure tray icon is themed in all cases

UI: Set restart state when there is no media

UI: Allow adjusting media slider with arrow buttons

Consistent with modified default UI setting.

win-dshow: Add installer scripts for manual Virtual Cam registration

This adds two batch scripts to install and uninstall the virtual cam
devices for installations where the installer could not be used.  Most
commonly, this is for portable installations or those who prefer the
.zip file.

Allows the ability to install extra data from a specific absolute path
rather than a path relative to the cmake current source dir.  Useful if
say I want to generate data files in to the cmake binary folder rather
than put them in the data folder of the cmake source dir.

It seems like YouTube applies nonlinear-to-linear sRGB, and
linear-to nonlinear-709 transformations to uploaded videos now. This
makes sRGB too dark on their platform for video players that alias 709
as sRGB, which is almost everyone. Make 709 the default to keep peace.

UI: Refine context bar

This adds spacing between the timer and duration labels in the media
controls. The vertical alignment of the labels have been fixed as well.
And the width of the source label has also been widened.

This allows the user to adjust the media slider with the left
and right keyboard arrows. It is currently set to adjust
by 5 second increments.

When there is no media, set the media to the restart state.
Currently, this only affects the VLC source, as the media
source doesn't use the OBS_MEDIA_STATE_NONE, at this time.

UI: Don't save invalid colors via Source Toolbar (Freetype 2 Source)

UI: Fix rec time left not showing in stats

UI: Fix memory leak when dropping files

UI: Fix compiler warning about needing parenthesis

UI: Fix source ref bug causing crash on exit

In 218b936b, the virtual camera was ignored when checking the active
state, which is kind of a lackluster solution.  Instead, this makes
SetupOutputs() a virtual function, and calls it before starting the
virtual camera to be more consistent with the rest of the outputs.

Because the window capture source updates its data whenever certain
properties are modified, this would cause a race condition because
source updates normally happen in the graphics thread.  To solve this
for the time being, put access to that data within a mutex when updating
or updating visibility.

When the feature was added to allow slashes in recording/replay
filenames to automatically create directories, auto-remux was not
accounted for, and all filenames were assumed to be complete.  It used
fi.completeBaseName() to construct the new name which would only add the
last part after the last slash as the filename, causing the remuxed file
to save in the base directory rather than the intended directory.  This
fixes that by simply using the input string as the output string,
removing the extension, appending the new extension.

Because the virtual camera stops immediately when you call
obs_output_stop() rather than with a delay like other outputs, it
exposed a bug where the tray icon would show OBS as active when stopping
the source, regardless of the fact that it was stopped.  The bug was
that the expression used to activate the tray icon did not check to make
sure that the output was actually active, so add that to the expression.