libobs/UI: Add Property Grouping

Property groups are implemented in the UI using QGroupBox, which support
both the normal and checkable version of them.

Property groups allow multiple properties to be combined into a single
visual group and thus can be used to reduce visual clutter and improve
user experience by giving additional context to a property. The name of
a child of a group is not affected by the group and thus all property
names must still be unique.

A new parent field has been added to obs_properties_t to ease the
tracking of existing properties. That way properties inside a group will
also be able to verify that they have a unique name.

UI: Correct custom property implementation

Don't override the theme color settings for the Projector.
If required, the background color of the projector can be changed via

OBSProjector {qproperty-...}

record placed after "OBSQTDisplay {qproperty-...}" section in the theme
file (qss).

- Fixes Q_PROPERTY macro syntax
- Removes excessive notification declaration and slot
- Removes unneeded dynamic property
- Improves Themes versatility

vlc-video: Enable subtitle track selection

If custom theme for obs UI has no record about background custom
property in the qss file, then application can set random color per
display initialization. This fixes this issue.

deps/obs-scripting: Expose obs_output_output_caption_text1 to scripts

libobs: Fix shader for GLSL

vec4 to vec3 truncation fix.

Ui scroll wheel events

libobs: Add support for F25-F35 hotkeys on Linux

libobs: Add function to remove properties

vlc-video: Enable audio track selection

UI: Add Linux AppStream metadata

Improve locales

UI: Add hotkey to toggle preview

obs-filters: Add luma key filter

Clear linux compiling warnings

libobs: Add minimum display duration to caption data

linux-capture: Add randr support

UI: Refactor Audio Settings UI and move Monitoring Device from Advanced

win-capture/graphics-hook: Fix try_lock_shmem_tex mutex  deadlock bug

It's possible that the mutexes used with shared memory capture to return
WAIT_ABANDONED if OBS is shut down abnormally while the mutex is locked.

Minor improvements

obs-ffmpeg: Bind network buffer size in the UI

libobs: libobs-d3d11: Fix blend alpha overflow

Ignore wheelEvent using subclass
slider,spinbox,combobox with eventhandlers:
wheelEvent - ignore if widget is not focused,
leaveEvent - clear focus when mouse leaves event.

Use these new subclass widgets in properties
to ignore wheelEvent when scrolling.

obs-studio: Create obs.rc out-of-tree using the build path

UI: Don't hide cursor over multiview

rtmp-services: added OnlyFans.com streaming service

UI: Fix size of output icon

CONTRIBUTING.rst: Improve commit guidelines

Few words about the commit's titles were added (capital letter).

UI: Fix remux dialog ignoring filename changes