TIF: Make constants and certain function SystemApi in TvInputServiceExtensionManager

Making constants defining standardized AIDL interfaces names and
registerExtensionIBinder() SystemApi so that they would be accessible by
OEMs and client apps on the system partition.

Bug: b/330366987
Flag: android.media.tv.flags.tif_extension_standardization
Test: atest TvInputManagerTest

Change-Id: I13273d344b2fcc6ebfb4490339b8c5bf9ce131ef