[Extra zoom mode] Update time picker to use platform view controller

[Extra zoom mode] Update time picker to use platform view controller
https://bugs.webkit.org/show_bug.cgi?id=184252
<rdar://problem/38804795>

Reviewed by Andy Estes.

Adjust for some small WKTimePickerViewController changes, and remove some files that we no longer need.

* UIProcess/ios/WKContentViewInteraction.mm:
(-[WKContentView presentViewControllerForCurrentAssistedNode]):
(-[WKContentView textInputController:didCommitText:]): Deleted.
(-[WKContentView textInputController:didCommitText:withSuggestion:]): Deleted.
(-[WKContentView textInputControllerDidRequestDismissal:]): Deleted.
* UIProcess/ios/forms/WKTextFormControlViewController.h: Removed.
* UIProcess/ios/forms/WKTextFormControlViewController.mm: Removed.
* UIProcess/ios/forms/WKTextSuggestionButton.h: Removed.
* UIProcess/ios/forms/WKTextSuggestionButton.mm: Removed.
* WebKit.xcodeproj/project.pbxproj:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@230217 268f45cc-cd09-0410-ab3c-d52691b4dbfc