Reactivate install session after user grants install permission

+ The install session is marked as "active" after user action was promted
and user grants permission to install the app.
+ Any session status listener will be able to get the correct state of
  the session and would not erronously consider a session idle.

Test: Untestable due to limitations of the framework
Bug: b/193606242
Fixes: b/193606242
Change-Id: I42b0147223f05a8bbe455e98f90935e9c1dfbf71