pane: Add settings to hide the tab bar buttons (#23752)

This PR adds the `show_tab_bar_buttons` under `tab_bar` that allows
hiding the "New", "Split Pane", and "Zoom" buttons to the left of the
pane tab bar.

Release Notes:

- Added a new `show_tab_bar_buttons` setting, under `tab_bar`, that
enables hiding the pane tab bar buttons.

docs/src/configuring-zed.md

@@ -714,7 +714,8 @@ List of `string` values
 ```json
 "tab_bar": {
   "show": true,
-  "show_nav_history_buttons": true
+  "show_nav_history_buttons": true,
+  "show_tab_bar_buttons": true
 }
 ```
 
@@ -738,6 +739,16 @@ List of `string` values
 
 `boolean` values
 
+### Tab Bar Buttons
+
+- Description: Whether or not to show the tab bar buttons.
+- Setting: `show_tab_bar_buttons`
+- Default: `true`
+
+**Options**
+
+`boolean` values
+
 ## Editor Tabs
 
 - Description: Configuration for the editor tabs.