Add tests for IMS#showSoftInput and IMS#onConfigurationChanged

Add more test cases for Ime visibility under different flags and system configs of IMS#showSoftInput and IMS#onConfigurationChanged.

Bug: 242838873
Bug: 240359838

Test: atest com.android.inputmethodservice.InputMethodServiceTest
Change-Id: I66ce0a525e6867a783da20188f0d657a3e70d90d