feat: asyncify pickers - except for live_grep (#709)

* something kind of works already

* yayayayayayayayayayayayayayayayayayayayayayayayayayayayayayayayaya

* use async for everything besides live jobs

* fix: fixup autocmds previewer

* fix: lints for prime

* temp: Add example of how we can think about async sorters

* feat: Allow picker to decide when to cancel

* fix: simplify scoring logic and tests

* fixup: name

* fix: Move back towards more backwards compat methods

* fixup: Remove results from opts

* fixup: remove trailing quote

* fixup: Attempt to clean up some more async items. Next is status

* wip: Add todo for when bfredl implements extmarks over the EOL

* wip

* fixup: got em

* fixup: cleaning

* fixup: docs

.gitignore

@@ -1,2 +1,4 @@
 build/
 doc/tags
+
+.luacheckcache