No-op: Move the language detection model service into the component.

This moves a bunch of code and renames TranslateModelService{,Factory}
to LanguageDetectionModel{,Factory}. Also introducing some iOS-specific names.

Bug: 354069716
Change-Id: Ib32a8060ca0c42df049b99ffaac9c3cc6be7dc85
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5831663
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Monica Basta <msalama@chromium.org>
Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Trevor Perrier <perrier@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Auto-Submit: Fergal Daly <fergal@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1353745}