Fix or disable some useless warnings

templates: Fix the remaining uncommitted changes

code: Fix encoder::ffmpeg causing recursive mutex lock on Singleton

Not sure why I did it any other way before - there's no benefit to the previous design, only downsides.

code: Fix incorrect behavior for encoder::ffmpeg

As we previously relied on an additional function call, we should now merge this call into the constructor.

code: Reorder and fix static initializers

These most likely require dependencies to be migrated to the new system.

ci: Build libOBS with MSVC on Windows

obs-studio does not yet support ClangCL, resulting in a broken build. We don't want to check if obs-studio is broken, we only want to check if StreamFX is broken.

ci: Fix CI failure

code: Disable profiling on MacOS

This may address a nullptr crash on MacOS with several features.

ci: Add validation for Copyright headers

Strictly enforce up-to-date copyright headers using CI/CD.

third-party: Update OBS Studio to 29.0.0-beta2