This method is needed for YouTube stream tests, because when all YouTube tests are ran, the signatureTimestamp is known (the sts string) so a different body than the body present in the mocks is send by the extractor instance.
As a result, running all YouTube stream tests with the MockDownloader (like the CI does) will fail if this method is not called before fetching the page of a test.
Add the origin and the referer headers with the https://www.youtube.com value for YouTube JSON POST requests.
Don't add the consent cookie header for the requests which use the youtubei/innertube API because it's uneeded.
Fix some tests and update YouTube mocks
Refactor all stream extractor tests to use new base class.
Remove check if upload date is in the past: this does not have to hold true: youtube premieres turn up in search results even though they are in the future
- Handle special cases for languages where the number is not shown
- Rework the Downloader base implementation, allowing for more
advanced things to be done
- Separate the localization from the content country (just like
YouTube let's the user choose both).