Move code processing inherited files and libraries to its own method (1/n)

These steps are not really about verification. They can be moved to
the install phase which however will increase boot time of staged APKs.

So we prefer to do them right before verification starts.

In later CLs, we will move the verification code to its own class.

Bug: 161121612
Test: atest CtsAtomicInstallTestCases
Test: atest CtsPackageInstallTestCases
Test: atest CtsStagedInstallHostTestCases
Test: atest CtsExtractNativeLibsHostTestCases
Change-Id: Ia2abed25be7fff144406f39fa5a1e4759578ff51