Register first view of Welcome Tour tutorial.

This CL registers the first view of the Welcome Tour tutorial and
sets up initial test coverage for the experience. The remainder of the
views will be registered in a follow up to minimize bloat in this CL.

Bug: b:275616974
Change-Id: I50a8d077214a31426fea8857a6141a16642a9de6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4402027


Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1128694}