Skip back for unknown sources

This change uses an appops observer to automatically relaunch the
package installer acativity to the front of the task when the user
chooses to allow installs from unknown sources.

Bug: 183960866
Test: atest CtsPackageInstallTestCases
Change-Id: I8fccb0b296752ba30e1cc19b719d964df893079a
1 file changed