Add log when clipboard smart actions shown

Refactors to pull the action classification into a separate class for
testing. Logic flow is unchanged.

Test: make statsd_testdrive && $ANDROID_HOST_OUT/bin/statsd_testdrive 90
Test: atest ClipboardOverlayControllerTest
Bug: 261201283
Change-Id: Ie931b2c11ef1a01c16147907d730d1dd6e5febe8