[cmake, tools] update CPMUtil and add support for CPMUtil bundled Qt, module updates, cleanups (#3289)

Support for bundled Qt, not through aqtinstall but rather my CI. Multimedia is
implemented too, works on both Windows and Linux, though we don't
actually use it so it doesn't really matter. Contains Declarative and all that so the Quick frontend will work once it becomes a thing.

Some options have changed, notably w.r.t LTO and faster
linker, which are now handled directly in the modules.

CPMUtil also has support for custom dirs (`PackageName_CUSTOM_DIR`) now. Probably most useful for adding external fragment shaders and whatnot.

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3289

docs/CPMUtil/AddQt.md

@@ -0,0 +1,28 @@
+# AddQt
+
+Simply call `AddQt(<Qt Version>)` before any Qt `find_package` calls and everything will be set up for you. On Linux, the bundled Qt library is built as a shared library, and provided you have OpenSSL and X11, everything should just work.
+
+On Windows, MinGW, and MacOS, Qt is bundled as a static library. No further action is needed, as the provided libraries automatically integrate the Windows/Cocoa plugins, alongside the corresponding Multimedia and Network plugins.
+
+## Modules
+
+The following modules are bundled into these Qt builds:
+
+- Base (Gui, Core, Widgets, Network)
+- Multimedia
+- Declarative (Quick, QML)
+- Linux: Wayland client
+
+Each platform has the corresponding QPA built in and set as the default as well. This means you don't need to add `Q_IMPORT_PLUGIN`!
+
+## Example
+
+See an example in the [`tests/qt`](https://git.crueter.xyz/CMake/CPMUtil/src/branch/master/tests/qt/CMakeLists.txt) directory.
+
+## Versions
+
+The following versions have available builds:
+
+- 6.9.3
+
+See [`crueter-ci/Qt`](https://github.com/crueter-ci/Qt) for an updated list at any time.