Keystore 2.0 SPI: KeyStoreKeys adopt Keystore 2.0

KeyStoreKeys can now be constructed from key entry metadata and key
descriptors as defined by the new Keystore AIDL spec.
AndroidKeystorePublicKey can now create the private key proxy.
KeyStoreKeys also cache the key characteristic, which should drastically
reduce the frequency by which the SPI has to call into the Keystore 2.0
daemon.

Test: None
Bug: 159476414
Change-Id: Ia0a7841582621897760be49d39dd5442b70b3aa0