vim2 (#3594)

- First round of vim tests

Add `observe_keystrokes` back to gpui2
Allow multiple actions to match a given key event

[[PR Description]]

Release Notes:

- (Added|Fixed|Improved) ...
([#<public_issue_number_if_exists>](https://github.com/zed-industries/community/issues/<public_issue_number_if_exists>)).

crates/editor2/src/test/editor_test_context.rs

@@ -170,6 +170,10 @@ impl<'a> EditorTestContext<'a> {
         keystrokes_under_test_handle
     }
 
+    pub fn run_until_parked(&mut self) {
+        self.cx.background_executor.run_until_parked();
+    }
+
     pub fn ranges(&mut self, marked_text: &str) -> Vec<Range<usize>> {
         let (unmarked_text, ranges) = marked_text_ranges(marked_text, false);
         assert_eq!(self.buffer_text(), unmarked_text);