[bookmarks] Add empty-state view as an item type

- Add new view type for the empty state.
- Remove SelectableListLayout-driven empty state code.
- Populate the new list type when there are no bookmarks

Bug: 41481889
Change-Id: I543b5b1ec6b256d4f108f96aebd2d3ecd83a1fd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5618133


Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@google.com>
Cr-Commit-Position: refs/heads/main@{#1313137}