be able to mute hashtags

### Problem I have

I'm not a fan of some #hashtag games people play on Mastodon. For example, when following #startrek there is an account that adds that hashtag to his #hangtrek. it's just annoying. another annoying hashtag is #hashtaggame. some people I follow will play this game and it's just... not something I care about at all.

### Solution I'd like

I'd like to mute that hashtag so I don't see it in my timeline or when looking at other hashtags. just filter them away with prejudice. using the filter tab works, but it would be nice to just tap a hashtag and then click mute for 7 days or whatever and the filter gets made.

### Alternatives considered

Perhaps what I'm looking for is generic filters to be more easy to make throughout the UI? I can block these hashtags now in the filters section.

### Other

(Also filters seem to be case sensitive so I have many different versions of #HashTagGames with different cases to remove them all)

(could be the cleanup of matching take awhile and I just keep adding different cases?)

Start in the existing filters section and trace how hashtag links are handled in the timeline and hashtag views. Check how filter durations and case matching currently work. Done means a user can mute a hashtag from the relevant UI for a chosen duration and no longer sees matching posts in their timeline or hashtag views.

Written by the indexing model from the issue text.