Move signature checking out of ApexManager

Now the check is in PackageSessionVerifier for both staged and
non-staged APEX. This ensures a consistent behavior between
staged and non-staged APEX when it comes to signature checking.

* Remove the dependency on ApexPackageInfo from ApexManager
  which helps us migrate from ApexPackageInfo.

* Performance slightly improved (measured on Pixel4a) for
  APEX signature checking:

  shim APEX: 13-16ms -> 10-13ms
  com.android.art: 340-355ms -> 160-180ms
  com.android.cellbroadcast: 165-180ms -> 79-85ms

  This is because the SigningDetails of the install session is
  reused without re-calculation.

Bug: 225756739
Test: atest CtsStagedInstallHostTestCases \
            StagedInstallInternalTest \
	    GtsStagedInstallHostTestCases \
	    com.android.server.pm.ApexManagerTest

Change-Id: I6e3adf0f3f80764dcdb9cc26ef281f25566e854e