Added hasSha256SigningCertificate to the PackageManager aidl Interface.

This change expanded the IPackageManagerNative aidl interface
with the hasSha256SigningCertificate function.

This allows services to verify application signatures via this
aidl interface.

Bug: 174605881
Test: verified the pm binder service runs correctly on local device.
Change-Id: Ibbaae0714be4f105387f2f712b7c6485be16d7e6