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

lua/telescope/finders/async_static_finder.lua

@@ -0,0 +1,41 @@
+local async_lib = require('plenary.async_lib')
+local async = async_lib.async
+local await = async_lib.await
+local void = async_lib.void
+
+local make_entry = require('telescope.make_entry')
+
+return function(opts)
+  local input_results
+  if vim.tbl_islist(opts) then input_results = opts
+  else input_results = opts.results end
+
+  local entry_maker = opts.entry_maker or make_entry.gen_from_string()
+
+  local results = {}
+  for k, v in ipairs(input_results) do
+    local entry = entry_maker(v)
+
+    if entry then
+      entry.index = k
+      table.insert(results, entry)
+    end
+  end
+
+  return setmetatable({
+    results = results,
+    close = function() end,
+  }, {
+    __call = void(async(function(_, _, process_result, process_complete)
+      for i, v in ipairs(results) do
+        if process_result(v) then break end
+
+        if i % 1000 == 0 then
+          await(async_lib.scheduler())
+        end
+      end
+
+      process_complete()
+    end)),
+  })
+end