Improve vim interactions with edit predictions (#24418)

* When an edit prediction is present in non-insertion modes, hide it but
show `tab Jump to edit`.
* Removes discarding of edit predictions when going from insert mode to
normal mode, instead just hide them in non-insertion modes.
* Removes zeta-specific showing of predictions in normal mode. This
behavior was only happening in special cases anyway - where the discard
of completions wasn't happening due to some other thing taking
precedence in `dismiss_menus_and_popups`.

Release Notes:

- N/A

---------

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Mikayla <mikayla@zed.dev>

crates/supermaven/src/supermaven_completion_provider.rs

@@ -110,10 +110,6 @@ impl InlineCompletionProvider for SupermavenCompletionProvider {
         false
     }
 
-    fn show_completions_in_normal_mode() -> bool {
-        false
-    }
-
     fn is_enabled(&self, _buffer: &Entity<Buffer>, _cursor_position: Anchor, cx: &App) -> bool {
         self.supermaven.read(cx).is_enabled()
     }