[Instagram] Add tagged_users to keywords for stories (#2582)

[Infinitay]

Closes #2582. Adds mentioned users on Instagram stories to the metadata extracted by gallery-dl.

Example usage: gallery-dl -u <username> -p <password> -o extractor.instagram.include="stories" --filter "'tagged_users' in locals() and '<filter_username>' in [x['username'] for x in tagged_users]" --mtime-from-date <instagram_url>

First it'll check to make sure if tagged_users is found within the list of keywords¹ with 'tagged_users' in locals() and then it will also check to see if the supplied username is found within the list of tagged users with '<filter_username>' in [x['username'] for x in tagged_users].

¹: Keywords as in the content's metadata that is displayed when using -K or -j or --list-keywords

on another note, why don't we implement a key check so that users don't have to add a <x> in locals() check to their filter

[mikf]

While testing your code, I couldn't find any reel_mentions data anywhere. Any stories with tagged users did so via stickers (story_bloks_stickers) and reels via usertags, which are now also supported (e85ddf3).

Do you have a concrete example for a story or anything that uses the data structure like you mentioned in #2582?

[Infinitay]

While testing your code, I couldn't find any reel_mentions data anywhere.

That's weird. When I searched the data for the tagged username it appeared under reel_mentions. Unfortunately I don't have an example at this time. I'll look into it more when I get the chance. Hopefully no more than 24 hours.

Thank you for the additions by the way.