Rename CrossProfileApps API as per API council feedback

Three changes:
1. android.content.pm.crossprofile - > android.content.pm
2. getProfileSwitchingIcon -> getProfileSwitchingIconDrawable
3. startMainActivity “user” parameter should be named “targetUser”

Test: atest FrameworksServicesTests:com.android.server.pm.CrossProfileAppsServiceImplTest
Test: atest frameworks/base/core/tests/coretests/src/android/content/pm/CrossProfileAppsTest.java
Test: atest cts/hostsidetests/devicepolicy/src/com/android/cts/devicepolicy/CrossProfileAppsHostSideTest.java

FIXES: 71818128

Change-Id: Icf9a6d1f8b6808935ffd79b43185c7b12235f349