libobs: Null check hotkey device on macos

CI: Fix framework symlinks when building osx app

rtmp-services: Increase FB max bitrate to 6Mbps

Allows the ability to save replays with a button rather than with the
keyboard if desired.

Closes obsproject/obs-studio#1954

Facebook Live now recommends 6000kbps for most streamers and the auto
capping is clamping users to 4000kpbs. This fixes the new suggested
setting.

UI: Streaming Settings Validation On Stream Start & User Help

When we use the server error to respond to user's failing to start a
stream it is slow to return an error and unclear to the user what went
wrong. This diff introduces a simple settings check before attempting
to stream and catch and explain specific URL/key issues to the user.

In the case of preset services we check there is a Stream Key before
attempting to start a stream.

In the case of "custom" we only verify there is a URL since for some
services that's all that is required or the user may use user/password
authentication.

Pull UI validation and its helpers to their own class. This class will
be used to validate forms and perform UI-action checks such as
checking stream keys aren't empty and in this diff now holds the logic
to ensure there is a source before the person starts a stream.

UI: Add Grid Mode to Scenes Widget

rtmp-services: Add Konduit.live

Closes obsproject/obs-studio#2224

UI: Allow switch to existing theme to reload

libdshowcapture: Update to latest submodule

This is useful for people modifying the currently selected theme.

UI: Don't modify theme if already set

This includes reselecting the existing selection, and cancelling out of
settings altogether. Takes a long time (7 seconds) in debug builds.

Decklink: Explicit casts for truncation warnings

libobs: Remove C99 hacks for older VC++

Fixes an issue where when trying to connect a Twitch account, and the
Twitch two-factor authentication check fails, the user will still
technically be logged in because the cookies will still be present, thus
when they try to click the "Connect" button again, it will skip the
login part (because they're already technically logged in), and just
give them the two-factor failure message without letting them enter in
their login information again.

In the current user interface code, OBSBasic::AddSceneCollection has a
qname parameter to allow explicitly specifying a name, but that code
path is unused in the UI code itself, and qname is typically empty.  If
qname is not empty, it does not properly generate a file name associated
with that specified scene collection name.  This fixes that issue.

CI: Add Cirrus-CI config for FreeBSD builds

UI: Fix source icons being shifted to the right

UI: Rename deprecated QPalette::ColorRole

Adds an option to the right click menu in the scenes widget to switch
modes. When in regular list mode, it'll let you select grid mode, and in
grid mode, it'll let you select list mode. Grid mode changes the scenes
widget to have a grid of buttons for scenes rather than a list, much
like XSplit.

UI: Fix Qt deprecation warnings