Allow to hide more buttons with the settings (#30565)

* project search button in the status bar
```jsonc
"search": {
  "button": false
},
```

* project diagnostics button in the status bar
```jsonc
"diagnostics": {
  "button": false
}
```

* project name and host buttons in the title bar
```jsonc
"title_bar": {
    "show_project_items": false
}
```

* git branch button in the title bar
```jsonc
"title_bar": {
    "show_branch_name": false
}
```

Before:
<img width="1728" alt="before"
src="https://github.com/user-attachments/assets/4b13b431-3ac1-43b3-8ac7-469e5a9ccf7e"
/>

After:
<img width="1728" alt="after"
src="https://github.com/user-attachments/assets/baf2765a-e27b-47a3-8897-89152b7a7c95"
/>


Release Notes:

- Added more settings to hide buttons from Zed UI

assets/settings/default.json

@@ -328,6 +328,10 @@
   "title_bar": {
     // Whether to show the branch icon beside branch switcher in the titlebar.
     "show_branch_icon": false,
+    // Whether to show the branch name button in the titlebar.
+    "show_branch_name": true,
+    // Whether to show the project host and name in the titlebar.
+    "show_project_items": true,
     // Whether to show onboarding banners in the titlebar.
     "show_onboarding_banner": true,
     // Whether to show user picture in the titlebar.
@@ -470,6 +474,8 @@
   "search_wrap": true,
   // Search options to enable by default when opening new project and buffer searches.
   "search": {
+    // Whether to show the project search button in the status bar.
+    "button": true,
     "whole_word": false,
     "case_sensitive": false,
     "include_ignored": false,
@@ -1002,6 +1008,8 @@
   "auto_update": true,
   // Diagnostics configuration.
   "diagnostics": {
+    // Whether to show the project diagnostics button in the status bar.
+    "button": true,
     // Whether to show warnings or not by default.
     "include_warnings": true,
     // Settings for inline diagnostics