Keystore 2.0 SPI: Fix contract between equals and hashCode 2

This fixes the contract between equals and hashCode in
AndroidKeystorePublicKey. The previous fix made only a reference
comparisson between certificate blobs. In this patch java.util.Arrays is
used to compare and compute the hash of the array.

Bug: 196118021
Test: See following CL.
Change-Id: I2b8b7e740fb377de39fd21f763e15cb00024b2fc