Add cursor_shape setting for the default editor (#17572)

Closes https://github.com/zed-industries/zed/issues/16451,
https://github.com/zed-industries/zed/issues/14447,
https://github.com/zed-industries/zed/issues/7203

Addresses but does not closes
https://github.com/zed-industries/zed/issues/5179

Expose cursor shape selection to users. Possibly controversial, since
block cursor seems preserved for vim and terminal. But the heart wants
what it wants?

Release Notes:

- Added a setting for `cursor_shape`. Can be `bar`, `block`,
`underline`, or `hollow`. Default is `bar`.

crates/editor/src/editor.rs

@@ -1904,7 +1904,7 @@ impl Editor {
             linked_editing_range_task: Default::default(),
             pending_rename: Default::default(),
             searchable: true,
-            cursor_shape: Default::default(),
+            cursor_shape: EditorSettings::get_global(cx).cursor_shape,
             current_line_highlight: None,
             autoindent_mode: Some(AutoindentMode::EachLine),
             collapse_matches: false,
@@ -11820,6 +11820,7 @@ impl Editor {
             cx,
         );
         let editor_settings = EditorSettings::get_global(cx);
+        self.cursor_shape = editor_settings.cursor_shape;
         self.scroll_manager.vertical_scroll_margin = editor_settings.vertical_scroll_margin;
         self.show_breadcrumbs = editor_settings.toolbar.breadcrumbs;