[extractor/zoom] Fix share URL extraction

[bashonly]

/share/ URLs need to be redirected before the file_id can be extracted, and the redirect URL path comes from an additional API request to the share-info endpoint.

I had to move some code around, since hypothetically we will want both types of webpages to be checked for password inputs if/when someone manages to fix password-protected video extraction. But otherwise I didn't touch the password validation code.

One thing to note is that the redirect URL/play ID returned from the share-info endpoint is dynamically generated. No two requests return the same ID (even for the same video). So for the video's id, I thought it best to just use whatever ID is in the user-provided URL, regardless of whether it is a play ID or a share ID.

Addresses #6677 (comment)

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