Global search through fuzzy picker

[matoous]

Describe your feature request

Global search could be more useful (subjective opinion) if there were live results available. Would it make more sense for global search (space + /) to pop fuzzy finder the same way for example space + f does for files currently?

[pppKin]

@archseer thought of this before, but ultimately it was just too troublesome(for me at least) to implement a special type of Picker and take care of the "search and update picker view" process. I'd love to help though now that I finally have some more time to work on helix! What do you have in mind?

edit: One straightforward way to implement this is to add a score_fn callback to Picker, so that everytime we type, we can start the search and feed the results back to Picker. However since global search is so expensive(can take seconds or even minutes), we'll need to integrate idle_timer in Picker. While we're at it, we should just somehow asynchronously feed the search results back to Picker, and provide a way to cancel the search midway. All of this, unfortunately, is not so easy to implement. We can start by waiting for idle_timer before Picker::score, though.

[archseer]

Closing this as a duplicate of #196 (we made that the tracking issue now)