Allow InputHintChecker only on Android V

The essential functionality for the InputHintChecker is only available
on Android V. Until recently the SDK we had been using did not contain
the corresponding VERSION_CODES constant for V, so we allowed the
InputHintChecker to attempt initialization on every U device. It does
not add a lot of overhead to do this initialization, but still it is
nice to avoid the unnecessary.

Bug: 330152494
Change-Id: I960ce07393db66668e69eb0c0eced7c573c1c467
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5704056
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Auto-Submit: Egor Pasko <pasko@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1326890}