A few fixes to do with the emulated command bar and Visual mode:

- Aborting ":" should leave us in normal mode with no selection.

- Don't exit Visual mode when we abort a search bar. To fix this, we send a null key event (instead of Escape) as the syntheticSearchCompletedKey.

- Update the cursor in Visual Mode as we search.

- Reset to original selection if we dismiss search in Visual Mode, even if the current search was a match.