Add three-bit hashes to `AutoFillUpload`.

Three-bit hashes coupled with existing secondary form signature will be
used to derive and introduce new server-side signatures:
go/autofill-signatures-more-data

Bug: 427425049
Change-Id: Ia6dce36a52c9215fe874ac9419230c6cf5c194f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6668420
Reviewed-by: Jan Keitel <jkeitel@google.com>
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Rahim Mammadli <rahimis@google.com>
Cr-Commit-Position: refs/heads/main@{#1479196}