Fix crash in IntentForwarderActivity

The crash was caused by trying to resolve an instant
app which is not allowed on the main thread, fixed it by
resolving on a background thread.

Fixes: 146141583
Test: atest IntentForwarderActivityTest
Test: atest ResolverActivityTest
Test: atest ChooserActivityTest
Change-Id: I250d682cf90870c7360eb66529be8c91fac266b1