security: In PolicyManager, make verifySha256WithRsaSignature simply take the signature bits.
security: In SelfVerifyPolicyManager, support verifying a Sha256WithEcdsaSignature.
tests: In TestEncodeDecodeData, in dumpData, show a Sha256WithEcdsaSignature.
encoding: In encode/decodeData, use the Signature base class to get the signature bits.