Fix update detection in app-installers

Fix update detection in app-installers

app-installers will need to detect update by itself to set
correct step for installation process. Therefore this patch
integrates previous workaround into common library code.

This will not requires changes in pkgmgr.

Introducing AppQueryInterface for each backend to provide.
This class will decide if update installation flow should
be forced or not. If pkgmgr backendlib would be developed
then this interface will require refactoring probably.

Please, note that tpk will need to provide own
AppQueryInterface instance.

Change-Id: Ic8d09b72227310fa4eb76bce882302c4291495d8