Bookmarks++: Show favicon correctly in star dialog

Pulls the correct favicon for the bookmark vs only using the default
favicon, in the bookmarks star entry point dialog. Also adds a white
background on the favicon instead of scaling it up.

Bug: 1425365
Change-Id: Ic1280ea132d9ab6ec8198de3e412b97c053332a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4348018


Reviewed-by: Caroline Rising <corising@chromium.org>
Commit-Queue: Emily Shack <emshack@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1118935}