Add android:exported tag

These are now required to be explicitly specified for
apps targetting API 31.

Bug: 195988762
Test: make
Change-Id: If1d8974150e14421a977674af7f0b0230af0e0be
Merged-In: If1d8974150e14421a977674af7f0b0230af0e0be
(cherry picked from commit f3d98cdf)