[Enhancement] Improve privacy / make Invidious less detectable

[unixfox]

Is your enhancement request related to a problem? Please describe.
YouTube is actively trying to restrict us. We should try to blend in with the crowd.

Describe the solution you'd like

• Randomize the user agent. Searx is already doing that: https://github.com/searx/searx/blob/master/searx/data/useragents.json
• Use a Firefox user agent. Google control chromium/chrome, so it can more easily detect some features that Invidious doesn't support compared to a real chromium/chrome browser.
• Randomize CONSENT cookie ID
• Randomize some headers (which ones?)
• Use a newer version of QUIC: related [Enhancement] Use the IETF draft-29 of HTTP/3 lsquic.cr#16
• Have a TLS fingerprint similar to Firefox or Chrome (hard to do in crystal) - https://fingerprint.com/blog/what-is-tls-fingerprinting-transport-layer-security/
• Use HTTP2 or HTTP3 - Modern browsers do not use HTTP1 anymore

Anything else?

[SamantazFox]

"Randomize CONSENT cookie ID" was done in #3893

[unixfox]

Added more things in the list to look like more of a browser.