CryptoPkg: Add EC public key PEM test coverage Add BaseCryptLib unit coverage for EC public key PEM functions: - EcGetPublicKeyFromPem - EcPublicKeyToPEM Test size discovery, undersized output buffers, invalid parameters, and round-trip public key comparison. Add MockBaseCryptLib support for the new EC public key PEM APIs. Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>