Parse package before enabling unknown sources

So that when we return from the settings app we do not have distinguish
between file and content-uri based install anymore

Test: Manually went through the following workflows:
      - Install from file
	- Unknown sources is already enabled
	- Unknown sources is not enabled yet
          - Return 0 from settings
            - unknown sources was enabled
            - unknown sources was not enabled
          - Return -1 from settings
            - unknown sources was enabled
            - unknown sources was not enabled
      - Install from content URI
        - Unknown sources is already enabled
        - Unknown sources is not enabled yet
          - Return 0 from settings
            - unknown sources was enabled
            - unknown sources was not enabled
          - Return -1 from settings
            - unknown sources was enabled
            - unknown sources was not enabled
Fixes: 31328285
Change-Id: I1d23f2ba9a835f7bffc59108565b286aeb675411