[Autofill] Rewrite FormFieldData::form_control_type to a member function

This CL applies the rewriter from crrev.com/c/5422009 to convert
the public data member FormFieldData::form_control_type into a private
member with a public member functions FormFieldData::form_control_type()
and FormFieldData::set_form_control_type().

This CL is part of a larger rewrite to turn Form[Field]Data into
classes.

Bug: 40232021
Change-Id: I55a3d8112b588ae29c3435311314d99a8ee1aafe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5447706
Reviewed-by: Ioana Pandele <ioanap@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Dominic Battre <battre@chromium.org>
Auto-Submit: Christoph Schwering <schwering@google.com>
Cr-Commit-Position: refs/heads/main@{#1287489}