[Android] Move autofillSnackbarController to //c/b/ui/autofill.

Previously, this controller was located in //c/b/ui/autofill/payments.
Now it will be used to inform the user about plus address
filling during full address form filling. To prepare for this change,
this CL moves the relevant C++ classes to the new location.

Relevant section in the design doc: http://shortn/_cLwuupWVZ7

Bug: 363695013
Change-Id: I32976c0aaf6fff4487f0a9ffaae3cf643b6fdee3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5920464
Reviewed-by: Jan Keitel <jkeitel@google.com>
Commit-Queue: Timofey Chudakov <tchudakov@google.com>
Cr-Commit-Position: refs/heads/main@{#1366813}