Add asynchronous HTTP and bulk fetching to enhance performance

[kaya70875]

No description provided.

[0xRaduan]

any chance this could get a review @jdepoix ?

[jdepoix]

Hi @0xRaduan @kaya70875,
First of all, thank you for your contribution @kaya70875!
I only had a very brief look at this, but it does not seem to follow the approach that has been discussed in #514 (refactoring TrascriptListFetcher to be async and wrapping sync call with asyncio.run in YouTubeTranscriptApi). Refactoring TrascriptListFetcher instead of adding TranscriptListFetcherAsync, would also make the code much easier to review, as it seems to contain a lot of copy-pasted code from TranscriptListFetcher.
I will have a closer look at this if these changes get implemented! 👍

[kaya70875]

@jdepoix Thanks for feedback. I guess I misunderstood, I thought we should not refactor anything and use existing modules to create YoutubeTranscriptAsyncApi class. That's why there is too much code duplication.

I'll refactor my PR accordingly based on your suggestions.