[ADI][10/N] API for installer to setExtensionParams

+ SessionParams.setExtensionParams
+ Make some previously added installer-facing APIs public
+ Return extensionResponse to installer for blocked installs

FLAG: android.content.pm.verification_service

BUG: 360129657
Test: atest frameworks/base/services/tests/PackageManagerServiceTests/server/src/com/android/server/pm/PackageInstallerSessionTest.kt
Test: cts tests to be added
API-Coverage-Bug: 367776952

Merged-In: Ibc45afe6b100a5f62e4c6a5cfcf20e6ef45cb305
Change-Id: Ibc45afe6b100a5f62e4c6a5cfcf20e6ef45cb305