project_panel: Add Sticky Scroll (#33994)

Closes #7243

- Adds `top_slot_items` to `uniform_list` component to offset list
items.
- Adds `ToPosition` scroll strategy to `uniform_list` to scroll list to
specified index.
- Adds `sticky_items` component which can be used along with
`uniform_list` to add sticky functionality to any view that implements
uniform list.


https://github.com/user-attachments/assets/eb508fa4-167e-4595-911b-52651537284c

Release Notes:

- Added sticky scroll to the project panel, which keeps parent
directories visible while scrolling. This feature is enabled by default.
To disable it, toggle `sticky_scroll` in settings.

assets/settings/default.json

@@ -617,6 +617,8 @@
     // 3. Mark files with errors and warnings:
     //    "all"
     "show_diagnostics": "all",
+    // Whether to stick parent directories at top of the project panel.
+    "sticky_scroll": true,
     // Settings related to indent guides in the project panel.
     "indent_guides": {
       // When to show indent guides in the project panel.