Extract cached package info from ApexManager

A step toward storing all package information including both APK and
APEX in PMS which be the source of truth for all queries about package
info.

* ApexPackageInfo stores PackageInfo for parsed/scanned APEX which
  makes migration easier.
* Now ApexManager stores only APEX specific data like APEX services or
  APK-in-APEX.
* ApexManager#getPackageInfo calls are replaced by ApexPackageInfo

Bug: 225756739
Test: atest com.android.server.pm.ApexManagerTest \
            android.content.pm.cts.PackageManagerTest \
            CtsPackageInstallTestCases \
            CtsStagedInstallHostTestCases \
            StagedInstallInternalTest \
            CtsInstallHostTestCases \
            DeletePackageHelperTest \
            DistractingPackageHelperTest \
            PackageFreezerTest \
            PackageManagerServiceBootTest \
            PackageManagerServiceHibernationTests
Change-Id: I875c2096029fc03b03ac3c65a968bff154676989