Build a sitemap manager to keep track of breadcrumbs

- Have a new db to track parent-child page relation at index time.
- Make a registry class to track (in IA) which page host what type of
  sub pages.
- Make a manager class that queries the db as well as IA to compute
  breadcrumbs

Fix: 32936784
Test: RunSettingsRoboTest

Change-Id: I5f1583fae772c3d477d2ad186e111b79cc3e41aa