Add ImeTargetVisibilityPolicy functions for applier

Add following utility methods into ImeVisibilityApplier:
  - showImeScreenshot
  - removeImeScreenshot

IMMS could use those API after this change. Also introduce new reasons
for those operations tracking.

This change only build the dependency between
ImeVisibilityApplier and ImeTargetVisibilityPolicy and didn't change
any behaviors.

Bug: 258048231
Test: atest DefaultImeVisibilityApplierTest

Change-Id: I2e1e4bc106fc14aa65825ee82dc09390422951c5