project_panel: Add bold_folder_labels setting (#47631)

This setting brings Zed in parity with Sublime's `bold_folder_labels`.

The settings does just that, it makes directory labels bold. This
setting is
particularly useful for those who turn icons off, but do need a visual
queue (besides the chevron) to quickly tell apart files and folders.

Note: This PR depends on
https://github.com/zed-industries/zed/pull/47629.
Otherwise, the setting will appear to have no uneffect (unless you're
using a custom UI font). ZedSans has "bold" today, but that's too thick
for the project panel.

<img width="2282" height="1545" alt="zed-project-panel"
src="https://github.com/user-attachments/assets/63ccacc0-c00a-48b2-8e70-923aa6717956"
/>

Release Notes:

- Added `project_panel.bold_folder_labels` to show folder names with
bold text in the project panel (defaults to `false`).

docs/src/reference/all-settings.md

@@ -4376,6 +4376,7 @@ Run the {#action theme_selector::Toggle} action in the command palette to see a
     "indent_size": 20,
     "auto_reveal_entries": true,
     "auto_fold_dirs": true,
+    "bold_folder_labels": false,
     "drag_and_drop": true,
     "scrollbar": {
       "show": null
@@ -4528,6 +4529,30 @@ Run the {#action theme_selector::Toggle} action in the command palette to see a
 }
 ```
 
+### Bold Folder Labels
+
+- Description: Whether to show folder names with bold text in the project panel.
+- Setting: `bold_folder_labels`
+- Default: `false`
+
+**Options**
+
+1. Enable bold folder labels
+
+```json [settings]
+{
+  "bold_folder_labels": true
+}
+```
+
+2. Disable bold folder labels
+
+```json [settings]
+{
+  "bold_folder_labels": false
+}
+```
+
 ### Indent Size
 
 - Description: Amount of indentation (in pixels) for nested items.