Move Glic settings page

This moves the Glic chrome://settings page from a top-level menu item
into a subpage under the existing AI experiences page. This requires
merging glic_data_page into glic_page since these are now in a nested
section.

Fixed: 393445109
Change-Id: I58575b049635969977cd00ba2f19cd243d91d225
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6305388
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: Ian Vollick <vollick@chromium.org>
Reviewed-by: Ian Wells <iwells@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1426630}