Editor: Add shortcut to toggle line numbers (#8642)

Following #7665, I've added a keymap to quickly hide and show gutter
line numbers.

`ctrl-l` and `cmd-l` were taken, so I've bound it to `cmd-;`. 



https://github.com/zed-industries/zed/assets/138762/365d2a7c-b775-4486-8389-edafe59b2a87

Release notes:

- Added `editor: toggle line numbers` command and default keybindings
(`cmd-;` on macOS).

---------

Co-authored-by: Thorsten Ball <mrnugget@gmail.com>

crates/editor/src/element.rs

@@ -275,6 +275,7 @@ impl EditorElement {
         register_action(view, cx, Editor::open_excerpts);
         register_action(view, cx, Editor::open_excerpts_in_split);
         register_action(view, cx, Editor::toggle_soft_wrap);
+        register_action(view, cx, Editor::toggle_line_numbers);
         register_action(view, cx, Editor::toggle_inlay_hints);
         register_action(view, cx, hover_popover::hover);
         register_action(view, cx, Editor::reveal_in_finder);