Reland "[unified-consent] Add subpage for sync data type toggles"

This is a reland of c62a1965a1ecd3ef8701679df3fbf26186219569
- route.js is imported in sync_controls.html.
- There was a dependency issue between sync_page and sync_controls,
  because sync_controls used a method from sync_page, and sync_page
  imported sync_controls.
  This is solved by firing an event from sync_controls instead.

Original change's description:
> [unified-consent] Add subpage for sync data type toggles
>
> - Add advanced sync subpage for configuration of sync
>   data types.
> - Add row "Manage sync" to sync_page that links to this subpage.
> - When the user goes through the sign-in flow to customize
>   settings and navigates to the advanced sync page, sync
>   doesn't start yet and the snackbar to cancel sync is shown.
>   When the user leaves the sync and the advanced sync page,
>   sync will start.
>
> Additional changes:
> - Change "Sync and personalization" to "Sync".
> - Change "Manage synced data on Google dashboard" to "Data from Chrome sync".
> - Rename people_page_sync_controls.js to people_page_sync_controls_test.js.
>
> Screenshots:
> https://drive.google.com/file/d/1DTa1gcdNc6WihGAawKzHseLEBgpFjegm/view?usp=sharing
> https://drive.google.com/file/d/1sn42U_nlkihUhRX2REY1XDBr5YmWxM7C/view?usp=sharing
>
> TBR=jochen@chromium.org
>
> Bug: 912598
> Change-Id: Id7b3f7121aac49fe643f3ef14726e98bc40b1ec6
> Reviewed-on: https://chromium-review.googlesource.com/c/1370282
> Reviewed-by: Thomas Tangl <tangltom@chromium.org>
> Reviewed-by: Scott Chen <scottchen@chromium.org>
> Commit-Queue: Thomas Tangl <tangltom@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#616704}

TBR=jochen@chromium.org,scottchen@chromium.org

Bug: 912598
Change-Id: I67396595945aab73fcc6d7bdb14f787e98aae887
Reviewed-on: https://chromium-review.googlesource.com/c/1378858
Reviewed-by: Thomas Tangl <tangltom@chromium.org>
Commit-Queue: Thomas Tangl <tangltom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617032}
13 files changed