This better matches upstream's FindOpus.cmake file, and it will make
using upstream's FindOpus.cmake file easier.

With this patch I've deleted a few find modules that are now unused
since the vcpkg transition, as the CMake code now forces CONFIG mode for
Catch2, fmt and nlohmann_json.

I've then simplified the lz4, opus, and zstd modules by exclusively
using pkg-config. They were using it already, but were ignoring the
result. Also, I believe that manually looking for libraries was required
for Conan to work, and it is thus not needed anymore.

Lastly, I believe that there is no platform that ships these system libs
without pkg-config/pkgconf, so requiring it should be fine.

ci: use dep5 for GitHub issue template files

yuzu: Add incremental steps to volume hotkeys

Revert "ci: Enable building with Visual Studio 2022"

externals: Use yuzu-emu/discord-rpc to provide Discord integration

Our fork includes a commit to disable clang-format, preventing the dirty
flag from being set when building yuzu on CI.

[Audio] Avoid an out-of-bounds span write in depop prepare

ci/linux: Exclude libwayland-client from AppImage

build: Ship vcpkg dlls with MSVC pr-verify builds

gpu_thread: Use the previous MPSCQueue implementation

service: irs: Implement clustering processor

applet/swkbd: Implement optional symbol keys 

exit gracefully on sigint/sigterm

chore: make yuzu REUSE compliant

As mentioned in the previous commit, `reuse lint` can be used to ensure
that copyright information is always present and up to date.

This adds a GitHub Action that does just that, using the official
fsfe/reuse-action

[REUSE] is a specification that aims at making file copyright
information consistent, so that it can be both human and machine
readable. It basically requires that all files have a header containing
copyright and licensing information. When this isn't possible, like
when dealing with binary assets, generated files or embedded third-party
dependencies, it is permitted to insert copyright information in the
`.reuse/dep5` file.

Oh, and it also requires that all the licenses used in the project are
present in the `LICENSES` folder, that's why the diff is so huge.
This can be done automatically with `reuse download --all`.

The `reuse` tool also contains a handy subcommand that analyzes the
project and tells whether or not the project is (still) compliant,
`reuse lint`.

Following REUSE has a few advantages over the current approach:

- Copyright information is easy to access for users / downstream
- Files like `dist/license.md` do not need to exist anymore, as
  `.reuse/dep5`...

With our recent switchover from conan to vcpkg, we're shipping a few
more dll files, these need to be in the full zip.

    cp .\build\bin\*.dll .\artifacts\

also tacking on the fix where we're shipping scm_rev.cpp accidentally

externals: Use GitHub for FFmpeg

FFmpeg's own git repo seems to be down, so switch to GitHub like we use
for most externals.

This library causes issues in Vulkan driver detection.
libQt5MultimediaGstTools's dependencies seem to be the issue.

yuzu, network: Add room service and UI configuration

Co-Authored-By: Narr the Reg <5944268+german77@users.noreply.github.com>