Add APIs to allow broadcaster to share identity with receivers

This commit adds APIs to allow a broadcasting app to share its
identity with the receiver(s) that will receive the broadcast and
to allow receivers to obtain the uid and package name of the
broadcasting app.

Bug: 259743961
Test: atest ShareIdentityTest
Change-Id: Ibe9df2b44e414ab92adbf44cd5b4c9eabecb7ee1