[pm/metrics][5/n] add installerUid in InstallSource

This is to allow metrics to easily obtain the UID of the installer
package. This can also be used to idendify the user that the installer
was called from.

+ Validate installer package name when it is set in the installation
  session. If not valid, clear it.

BUG: 249294752
Test: to be added
Change-Id: Ie7b8fd1515709e068b948088d54163b54b980dfb