Enable ASM when targeting C

Enables the ASM logic if the app targets C and all relevant feature flags are on and the app is opted in (either voluntary or forced).
This also moves the compat change flag to the BackgroundActivityStartController and removed an orphaned flag.

Bug: 416033243
Flag: android.security.asm_restrictions_enabled
Test: atest ActivitySecurityModelTest (TODO)
Change-Id: I6623752fc6765f9e2a63bffcaeb2ef8ffd18c892