ffmpeg: add new external libs added in 7.1

[jopejoe1]

Adds the new external libs added in FFmpeg 7.1, I have tested lc3 and vvenc, but I could not test lcevcdec as I did not find a video file with that encoding or an encoder to encode into it. Edit also tested lcevcdec now.

lc3 and vvenc can be tested with the following:

# Testing vvc
## Encoding
ffmpeg -f lavfi -i testsrc -t 10 -c:v vvc /tmp/test.vvc
## Decoding
ffmpeg -i /tmp/test.vvc -c:v hevc /tmp/decoded-vvc.mkv

# Testing lc3
## Downloading Sample file
curl "http://fate-suite.ffmpeg.org/aac/al_sbr_cm_48_2.mp4" -o /tmp/sample.mp4
## Encoding
ffmpeg -i /tmp/sample.mp4 -ac 2 -c:a lc3 /tmp/test.lc3
## Decoding
ffmpeg -i /tmp/test.lc3 -c:a aac /tmp/decoded-lc3.aac

# Testing lcevc-dec
## Downloading Sample file
curl "https://d3mfda3gpj3dw1.cloudfront.net/vn9s0p86SVbJorX6/lcevc_vn9s0p86SVbJorX6_2.mp4" -o /tmp/lcevc-sample.mp4
## Decoding
ffmpeg -i /tmp/lcevc-sample.mp4 -filter lcevc /tmp/decoded-lcevc.mp4

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[jopejoe1]

Found some samples for lcevc-dec and added information on how to test it in the description.

[SuperSandro2000]

otherwise lgtm