[Autofill] Rename ServerFieldType to FieldType 5/16

This CL does the renaming in ios/chrome/browser/autofill and
//ios/chrome/browser/ui/autofill.

Produced by
$ git ls-files ios | \
  grep '\.\(h\|cc\|mm\)$' | \
  xargs grep -l 'ServerFieldType' | \
  xargs sed --in-place -s 's/\<ServerFieldType\>/FieldType/g'

Bug: 1511368, 1007974, 1488408
Change-Id: I951ac16e85a7c20038476ed199dae196a67b6102
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5123395
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Auto-Submit: Christoph Schwering <schwering@google.com>
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1238064}