[UNO-d] Add history sync opt-in pill expansion

It adds the initial implementation of the history sync opt-in pill
expansion (https://screenshot.googleplex.com/o5JnPp9XTohTapC - internal
only).

The pill is shown right after `Hi, <username>` message for 60 seconds.
It should only be shown if the user is eligible to sync i.e. the user is
signed in, there are no errors and the sync is NOT disabled by the
policy.

Rate limiting the pill expansion, triggering it on users' inactivity,
actions on click and closing once the user clicks on it will be added in
future CL(s).

Bug: 407964550
Change-Id: I4afd3432df170df308cfd7c6541b22e9c36fcfab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6422018
Reviewed-by: Amelie Schneider <amelies@google.com>
Reviewed-by: Ryan Sultanem <rsult@google.com>
Commit-Queue: Ernest Nguyen Hung <ernn@google.com>
Cr-Commit-Position: refs/heads/main@{#1447108}