Hide "Send feedback" button if no target exists.

This change hides the "Send feedback" button  when a target for
the intent is not found. This will ensure the button is not
visible in cases when clicking it would have done nothing.

Bug: 283239837
Flag: com.android.settings.flags.datetime_feedback
Test: Test: atest TimeFeedbackPreferenceControllerTest.java
Change-Id: I8bb18c313925a7dc7ac07a1fb4c2f9e2d98352db