[iOS] Change "Clear Browsing Data" button to a toolbar button

- This change is behind the new-clear-browsing-data-ui flag.
- Make the CBD button (in TableView) a toolbar button to conform to the new design.

Bug: 935346
Change-Id: I25487b9f5f191f51cc2db020f45105997d7810ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520604
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Huanzhong Huang <huanzhong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641835}
3 files changed