[Feature request] localized YouTube content

[iBicha]

Is your feature request related to a problem? Please describe.
Invidious supports localization, but YouTube content is currently always in English (param hl=en).
Some YouTubers localize things like video titles and descriptions.
For example, you can open https://www.youtube.com/watch?v=Sqr-PdVYhY4 with YouTube in english or in french. Title and description are translated.

Describe the solution you'd like
Invidious should support the hl param everywhere across the website as well as the API, similar to the region param. Useful for the content, and also for the search / search suggestions.
Arguably, if someone sets Invidious to a certain language, they probably will appreciate the YouTube content being in that language as well

Describe alternatives you've considered
Do nothing

Additional context
There are some considerations to this I guess - such as how caching will work (only cache english? Will this impact performance on popular instances?)

[SamantazFox]

The reason we can't reasonably do that is that all the strings with numbers (like "8 days ago", "1.4M subscribers", "4.6B views") will need a separate parser for each language. I think there was another issue discussing that, but it might have been closed.

Edit: relevant comment(s):

• non-original title for video in english #1356 (comment)