[Feature Request] Allow selecting blacklisted codecs

[CTCaer]

Hello,
I'm developing a hw decoder based on ffmpeg for all Nvidia Tegra platforms (X1 and up).

By default, chromium allows for H264 and VP8 to fallback into FFMPEG so these ones are the important ones (without recompiling it).
My plan is to ship a custom libffmpeg.so as it's very easy to compile and ship into an apt repo.

Most (maybe all) 4K videos are enabled for AV1/VP8/VP9.
It would be nice for the tegra userbase to be able to select H264 and VP8 as supported codecs and thus enabling 4K videos.

Thank you for your time.