Mark methods on CryptographyClient as const within KeyVault Keys

[ahsonkhan]

Even though this SDK has shipped/GA'd, marking non-const methods as const is a non-breaking change so we can safely make this update and adhere to the C++ guidelines.

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-keys/inc/azure/keyvault/keys/cryptography/cryptography_client.hpp

Lines 130 to 132 in eaadd48

	Azure::Response<DecryptResult> Decrypt(
	DecryptParameters const& parameters,
	Azure::Core::Context const& context = Azure::Core::Context());

Other KeyVault Keys clients like KeyClient are already correctly marking the methods as const, so we only need to update CryptographyClient.

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-keys/inc/azure/keyvault/keys/key_client.hpp

Lines 123 to 127 in eaadd48

	Azure::Response<KeyVaultKey> CreateKey(
	std::string const& name,
	KeyVaultKeyType keyType,
	CreateKeyOptions const& options = CreateKeyOptions(),
	Azure::Core::Context const& context = Azure::Core::Context()) const;

SDK Clients are designed to be immutable as per the guidelines, so it should be safe to mark them as const so that a user referencing client instances as const& will be able to call any of the marked methods:

✅ DO declare all client functions as const since service clients are intended to be immutable.

cc @LarryOsterman, @RickWinter

Similar to:
#6328
#6329
#6330

Codegen issue for context: https://github.com/Azure/autorest.cpp/issues/464