[iOS] Create Consolidated Coordinator for GLIC

This CL starts the foundation for an MVC that will hold and handle the
GLIC promo and consent MVC logic. Currently GLIC promo and consent are
in independent systems which doesn't make sense since in some user
flows, the promo will lead to the consent UI.

Bug: 418752929
Change-Id: I6386d2f1e1659845351dcd05b70a073d009203a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6564687
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Auto-Submit: Joemer Ramos <joemerramos@google.com>
Cr-Commit-Position: refs/heads/main@{#1462666}