[mullet m2] Filters interesting fields based on the last targeted ones.

This CL allows to filter the fields to be filled, after a form
interaction depending the last granularity.

If for instance, an user chooses to a specific field to be
filled, GetLastServerFieldTypesToFillForSection will return a set of
fields with one value only. Which choose, to eventually tell
the manager (and in a follow up CL the suggestions generator)
that we want to filter out every field in the form (via SkipStatus)
that does not match the triggering field. Similarly if the user chooses
group filling, we make possible that in the next interaction,
only fields that match the triggering field group is
taken into account.

Demo: https://screencast.googleplex.com/cast/NTM4MzczNzYxNjM2NzYxNnwyYzdkZDIwNC0zMg

Bug: 1459990
Change-Id: I626a5826fdcb12974e47196c698f7233dedbd3a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4863565


Reviewed-by: Florian Leimgruber <fleimgruber@google.com>
Commit-Queue: Bruno Braga <brunobraga@google.com>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1197149}