Initial implementation of global search

[pppKin]

Since we haven't figure out how to properly implement a global search feature yet #196 , I hope this could at least be an inspiration of an potential better design:)
This implementation bind space + / to display a prompt (like the search prompt), and on Enter, start the search, gathers the result and pop up a FilePicker. A few necessary changes are made, such as regex_prompt, which now accepts an extra callback that would be invoked once Enter is pressed.
Feel free to close this if we figure out something better later.

[pppKin]

Some improvements that can be made:

1. Support cancellation. It appears that if Esc is pressed, the show_picker future placed on jobs list will not be dropped.
2. Async search. Currently the search runs on the main thread which blocks the user from doing anything before the search is completed.

[kirawi]

That's weird, why am I shown in the first commit?

[pppKin]

@kirawi Sorry but I have been scratching my head too. Perhaps I made a mistake when rebasing on master branch. Git did not complain anything though so I have no idea where I went wrong:\

[kirawi]

Not sure, I'm no git whiz 😅 Maybe it's possible to remove me as the author?

[pppKin]

I did another rebase and force pushed to solve the issue.

[cossonleo]

What's status of this pr?

[archseer]

Sorry for the delay, I finally did a full review here. I think it's a good first implementation, I'd still like to add a live search prompt in the future though 👍🏻

[archseer]

Why clone here? Can't you make it a move closure? .run(move || {

[pppKin]

WalkParallel::run takes a callback that returns a Box<dyn FnMut(Result<DirEntry, Error>) -> WalkState + Send + 's>, which would capture searcher, matcher, all_matches_sx. So I think the clone is necessary here.

[pppKin]

Thanks for the solid advice! I'd love to keep working on this PR and I will work on these changes and rebase onto latest master as soon as I can. (I am currently occupied so maybe have to wait till this weekend)

[pppKin]

All changes are pushed and rebased onto latest master now. Let me know if you need me to rebase and squash the commits:)

In the future I would like to bring up the picker as soon as Enter is pressed, move the search to a worker thread, and dynamically append results to the picker. This particular picker then could, should we wished, have 2 input fields, one for modifying search pattern, one for fuzzy matching search results. Unfortunately this is not trivial to implement at the moment(for me at least), so it's just a thought now.

[archseer]

Great work!