[ie/soundcloud] Add formats extractor-arg

[bashonly]

The Soundcloud extractor needs to make an API call for every format available in order to extract the actual format URL (and other format metadata such as bitrate).

This is already a problem since this format endpoint has a rate-limit, and users frequently hit the rate-limit when extracting a playlist/batch of songs.

Ideally, lazy info dict would solve this problem. But now Soundcloud has introduced encrypted-hls (AES-128 HLS) formats, which are just dupes of the hls formats we already extract, so now every song makes almost double the requests to the rate-limited API endpoint.

Since lazy info dict still has a ways to go before merge, and since the hls-aes formats have severely compounded the problem, the best solution is to implement an extractor-arg to allow the user to configure which formats should actually be extracted.

hls-aes formats are excluded by default since they are dupes, but now users will be to request them if Soundcloud stops offering the unencrypted hls formats in the future.

Note: extracting the original/source quality download formats does not count towards the API rate-limit (it doesn't use the problematic endpoint) and therefore is not imapcted by this extractor-arg

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