Deprecate AMD AMF encoders

[Xaymar]

Explain the Pull Request

As the FFmpeg implementation of AMD AMF is in an even worse state than obs-amd-encoder, these encoders should not be used at all by any sane person. Therefore they are deprecated as of v0.12, with a warning that they'll be removed eventually.

Completion Checklist

• I have added myself to the Copyright and License headers and files.
• I will maintain this code in the future and have added myself to CODEOWNERS.
• I have tested this change on the following platforms:
  • MacOS 10.15
  • MacOS 11
  • MacOS 12
  • Ubuntu 20.04
  • Ubuntu 22.04
  • Windows 10
  • Windows 11

[GloriousEggroll]

just wanted to note that these encoders work well on linux using the proprietary AMF drivers, and perform much better than the FFMPEG VAAPI encoders built into OBS. I would recommend leaving them for linux usage. It even works if I roll back to older drivers on older cards like R9 390x. There is a new gstreamer VAAPI encoder plugin that works extremely well (in fact its the only one that can record 4k60 given a powerful enough card -- tested on 6900 XT). I am trying to push for that encoder to replace the current FFMPEG VAAPI open source encoder, but for the proprietary AMF drivers streamfx is literally our only option on linux, especially considering OBS upstream's AMF encoder is windows-only.

[Xaymar]

especially considering OBS upstream's AMF encoder is windows-only.

You should probably ask upstream to support Linux then. The FFmpeg integration of AMD AMF is horribly outdated and does not support any of the metadata required to make OBS Studio 28.0 work.