[Enhancement] /videoplayback proxy send requests like real YouTube client

[unixfox]

YouTube clients are now sending requests using POST method and with a protobuf body.

We should try to replicate this behavior.

FreeTube has already implemented such modification: https://github.com/FreeTubeApp/FreeTube/blob/5a4cd981cdf2c2a20ab68b001746658fd0c6484e/src/renderer/components/ft-shaka-video-player/ft-shaka-video-player.js#L1089-L1107

This implementation should be done in https://github.com/iv-org/invidious/blob/master/src/invidious/routes/video_playback.cr#L3

[Fijxu]

Implemented on my fork of http3-ytproxy https://git.nadeko.net/Fijxu/http3-ytproxy/commit/6885fcfc2827da8916bf0ba951d8800077825a44

And a little POC that works well but I don't know if it's implemented correctly: https://git.nadeko.net/Fijxu/invidious/commit/51c5a05b94998f70bed1b19c0bd8ebed8e7bf6de

Body:

[SamantazFox]

This format is called UMp, and requires to make a parser for the format this returns.
I've started to work on the thing some time ago, but it needs to be finished:
SamantazFox@cee3b2a

Also, with the upcoming companion, it might not be very relevant anymore.

[unixfox]

This format is called UMp, and requires to make a parser for the format this returns. I've started to work on the thing some time ago, but it needs to be finished: SamantazFox@cee3b2a

Also, with the upcoming companion, it might not be very relevant anymore.

the first step is not necessarily to handle UMP. but send the requests using POST method and the body here: https://github.com/FreeTubeApp/FreeTube/blob/5a4cd981cdf2c2a20ab68b001746658fd0c6484e/src/renderer/components/ft-shaka-video-player/ft-shaka-video-player.js#L1097

UMP can come later