Enable non-secure side to receive messages > 4K

AttestKeyResponse may be larger than 4K (always less than 8K) when
attesting an RSA key. This change allows the non-secure side to read a
response that may be larger than 4K by adding an additional bit
indicating the end of a response. If a message command has the
KEYMASTER_STOP_BIT set, then the non-secure side knows that the response
has been fully read.

Test: android.keystore.cts.KeyAttestationTest#testRsaAttestation passes
      with production attestation key and chain, when AttestKeyResponse is
      larger than 4K.

      Tested with other CTS tests when keymaster messages are smaller
      than 4K, still passes.

      Manual test to verify that a tipc error due to large message size is
      handled correctly.
Bug: 63335726

Change-Id: I8776ba7ca70da893648e15cfa770784ab31a2cb0