feat: refine results action

[fdschmidt93]

Putting this up for discussion.

Actual use cases if someone has telescope-fzf-native:

• fuzzy refining live grep
• dynamic lsp workspacye symbols

TO DO/DECIDE:

• What opts, if not all, should be configurable? If all, results can also be refined via feat: allow caching and resuming picker #1051 (done in stash) though with visible, unavoidable redraw from new picker
• Why is the prompt prefix not immediately updated?
• Remove default mapping once decided to keep this
• Fix highlighting after refinement
• Should this be the default for live_grep and grep_string on whitespace?

Currently sorter, keeping prompt/prefix/multi selection & showing prev prompt in prefix are configurable. Would need actions.generate from #1062 to override defaults.

Preview: shows prompt is not immediately updated while actual refinement is instant

refine.mp4

[kylo252]

I'm really happy that would be available soon, much better than my naïve implementation that we briefly discussed over on gitter/matrix last week.

Some notes:
I couldn't figure out how to add a highlight group for the previous queries. I'm guessing we can't keep the old one since it will become inconsistent once the results have been filtered, so it needs to be reapplied dynamically instead. Any ideas regarding that?

[Conni2461]

merging without docs for now, into dev branch

[Conni2461]

We can add more opts later, i prefer a more minimal feature over not having the feature.

Thanks for staring it @fdschmidt93 <3