Fix AwG suggesting to save password for the Chrome App

After showing add username dialog (it's shown when user saves a password
with empty username), AwG pops up proposing to save the password. This
happens because of using TextInputEditText ui element, which provides
autofill structure to AwG. This CL uses the ui element, which doesn't
provide autofill structure (and moves this element to a more shared
place).

Bug: 372415388
Change-Id: I8a53f801c6ab847662fa7a1c52c01b437b723e00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5965062
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Ioana Pandele <ioanap@chromium.org>
Commit-Queue: Anna Tsvirchkova <atsvirchkova@google.com>
Cr-Commit-Position: refs/heads/main@{#1373911}