In CMakeLists.txt, FIND_MODE is not defined here. This was moved from
UI/CMakeLists.txt in commit cb4d2ff7. In
UI/CMakeLists.txt, FIND_MODE is REQUIRED if DISABLE_UI is false or
undefined and ENABLE_UI is true. Since the same booleans are required
for the if-else branch in CMakeLists.txt where we try to find Qt, we can
set find_package to REQUIRED here as well.

UI: Don't attempt to resize parent group when changing cursor

UI: Fix Qt6 build issues

Qt6 enables Qt::AA_UseHighDpiPixmaps by default and will emit a warning
if you try to enable it. To prevent the warning, only set this on Qt5.

Explicitly include QFile to prevent a build failure with VS2019 and Qt6.

In Qt6, QTextStream::setCodec has been replaced by
QTextStream::setEncoding. However, all text is assumed to be UTF-8, so
we don't need to specify UTF-8 in Qt6.

https://doc.qt.io/qt-5/qtextstream.html#setCodec-1
https://doc.qt.io/qt-6/qtextstream.html#setEncoding

Our QT_UTF8(str) macro uses QString::fromUtf8(str) with no size
argument. In Qt5, QString::fromUtf8 uses a default value of -1 for the
size arg. If size is -1, it is taken to be strlen(str). In Qt6,
QString::fromUtf8 doesn't use a default value for the size arg, but has
the same behavior if you manually specify -1 for the size. Let's
manually specify -1 to maintain the same behavior between Qt5 and Qt6.

https://doc.qt.io/qt-5/qstring.html#fromUtf8
https://doc.qt.io/qt-6/qstring.html#fromUtf8

Make building against either Qt5 or Qt6 easier by checking the Qt
version used and loading the appropriate Qt Network DLL.

Fixes an issue where resizing a source did not resize the parent group.

This changes cleans up some deprecated functions that were removed in
Qt6. Some are placed behind version ifdefs and others are replaced for
their non-deprecated Qt5 version.

Closes obsproject/obs-studio#4264

closes #2951

fixes #2676

The UpdateSceneSelection function was doing the same thing as the
code in the SetCurrentScene function.

Unsure if the intrinsics imply ordering. Safer to assume they don't.

Clicked includes the release, whereas pressed occurs before.

Fixes some warnings generated by code analysis tools, removing redundant
checks etc.

The ternary operator promotes both sides to the same type if possible,
so it created and destroyed a temporary ComPtr. Found by PVS Studio.

"Ideal" is an absolute.

When enumerating the list of encoders offered by VideoToolbox,
there's no reason we can't use the returned ID, which allows us to
remove the hardware/software encoder specific functions. At the
same time, this does add a slight complexity when localizing the
encoder name, so we can fall back to the OS-provided encoder name
if there's not a match.

Previous versions of LuaJIT required setting linker options
-pagezero_size and -image_base.  This was accomplished in commit
c9224edb, but as of LuaJIT 2.1, this is no longer necessary, and
doing so results in the application being killed when run natively
on macOS ARM targets.

The timestamp returned by mHostTime in the AudioTimeStamp structure
is the current timestamp equivalent to mach_absolute_time(), which
is relative to the machine's time base. In order to convert this
to milliseconds, it's necessary to get the host's timebase with
mach_timebase_info() and scale the timestamp accordingly, since
the rest of the timestamp synchronization code expects the timestamp
to be in milliseconds.

This is effectively equivalent to the code which was previously in
libobs/util/platform-coca.m, but must be applied here instead.

macOS should use the function clock_gettime_nsec_np() to get the
current clock in nanoseconds, instead of manually using
mach_absolute_time() and manually adjusting the timebase. This
greatly simplifies the platform-specific code to manage the
current time in nanoseconds.

When calling D-Bus methods, three fields are required:

 * The bus name, which is what applications own when they
   want to expose themselves to D-Bus;

 * The object path, which represents a D-Bus object exported
   under a bus name;

 * The interface, which holds the methods and signals;

While out of pure coincidence all the D-Bus buses have a
matching interface name, it is technically incorrect to assume
that.

Add a new 'interface' field to service_info, and split the bus
name.

GDBus is more and better maintained than libdbus these days. In the
future, a potential Wayland-compatible capture plugin will need to
interact with D-Bus in a way that's way too complicated for libdbus,
and it won't be nice to have both libraries talking to the D-Bus
socket.

Replace the libdbus usage by GDBus. As it turns out, it results in less
code.

All D-Bus interfaces call the unique identifier that is returned by their
calls "cookie", so rename the 'id' field to 'cookie' to match that.

Closes obsproject/obs-studio#4263

There are too many issues with 20.04 to successfully build with
VirtualCam - the azure kernel is missing videodev headers. For now,
use 18.04 LTS directly for main CI builds.

Both 18.04 and 20.04 include clang-format-10 without issue.