Introduce the OBS_NIX_PLATFORM_WAYLAND enum value, and try to detect
it when OBS Studio runs by looking into the platform name.

Right now, linux-capture hard-depends on GLX. Disable it when
running under EGL.

Move the OBS_USE_EGL environment variable check to obs-app.cpp,
and set the OBS platform to be either OBS_NIX_PLATFORM_X11_GLX
or OBS_NIX_PLATFORM_X11_EGL.

This is a Unix-specific code. The only available platforms
at this point are the X11/GLX and X11/EGL platforms.

The concept of a platform display is also introduced. Again,
the only display that is set right now is the X11 display.

Currently, obs-nix.c is highly tied to the X11 display
server. It includes X11 headers directly, and make use
of X11 functions. Most of the code inside obs-nix.c that
is X11-specific is related to hotkeys handling.

Introduce a new vtable for hotkeys callbacks, that will
used by X11 and Wayland to expose their specific routines.
In this commit, only the X11 hotkeys vtable is implemented.

Move all the X11-specific code to obs-nix-x11.c, and add
a new function to retrieve the X11 hotkeys vtable.

List this dependency both under CI/install-dependencies-linux.sh, and
.github/workflows/main.yml.

To keep consistency with the EGL line

Introduce the EGL/X11 winsys, and use it when the OBS_USE_EGL environment
variable is defined. This variable is only temporary, for future commits
will add a proper concept of platform.

All the EGL/X11 code is authored by Ivan Avdeev <me@w23.ru>.

Move the GLX-related code to gl-x11-glx, and introduce gl-nix as
a winsys-agnostic abstraction layer. gl-nix serves as the runtime
selector of which winsys going to be used. Only the X11/GLX winsys
is available now, but later commits will introduce the X11/EGL
winsys as well.

The gl-nix code was originally written by Jason Francis <cycl0ps@tuta.io>

This is in preparation for the future abstraction layer (gl-x11-*)
and also to match the actual name of the windowing system. When
running under X11, we can glue OpenGL through GLX or EGL, so the
new file name matches that now.

The code is generated by https://glad.dav1d.de/

Bug is caused by the internal connection variables not being reset on
reconnect, leading OBS to both be unable to parse valid packets from and
send valid packets to the remote end.  This commit splits RTMP_Init off
into a new RTMP_Reset function, which resets these internal variables
without re-initing the rest of the library.  The original RTMP_Init
calls the new function, perfectly preserving the old behaviour while
adding a new reset function to address the issue with.

Fixes obsproject/obs-studio#2865

libobs + UI: Add Missing Files API & Dialog

Add display capture via Windows Graphics Capture

Another warning clean-up pass

While the current code only ever calls try_connect() with the input
argument 'device' in the range of 0 and MAX_DEVICES, this adds a check
to ensure that future code does not break the following sprintf.

In addition, use snprintf instead of sprintf to ensure that if anything
breaks, the sprintf does not lead to memory corruption. Again, the new
check should already make sure of that, but the additional effort of
using snprintf instead of sprintf is so low that it is worth to have a
little more security in the future.

Removes prior attempt to expose libcaption headers which really shouldnt
have public. This instead moves the obs-internal include out of the
public obs-scene.h and into it's implementation.

The same reasoning of the previous patch means we can also stop
force-disabling Qt/GLib integration.

After the recent CEF update, the GMainLoop-in-a-thread conflict seems to be
gone, which allows us to being back native dialogs.

In case no-one else initializes X11 locks do this as part of loading the
module.

Fixes #3479

Add PolyStreamer.com to services.json, and increment the version in
accompanying package.json

libobs directly depends on libcaption headers. So ensure they are
installed with obs' headers.

fixes #3925

Closes obsproject/obs-studio#3689

Closes obsproject/obs-studio#3689

Allows for identification of sources in studio mode

Copy patterns from WGC window capture, and BitBlt monitor capture.

Helper function to find DXGI output index of HMONITOR.

This also simplifies environment variable definitions

Add display capture support via winrt_capture_init_monitor. Almost all
of the existing window capture code is reused.

Rename winrt_capture_init to winrt_capture_init_window for symmetry.