Add KMS Generation Metadata (#1440)
Add KMS Generation Metadata (#1440)

This PR was generated using Autosynth. :rainbow:

Here's the log from Synthtool:
```
synthtool > Cloning googleapis.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:90f9d15e9bad675aeecd586725bce48f5667ffe7d5fc4d1e96d51ff34304815b
Status: Image is up to date for googleapis/artman:latest
synthtool > Running generator for google/cloud/kms/artman_cloudkms.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-kms-v1.
synthtool > Replaced 'Copyright \\d{4}' in src/V1/KeyManagementServiceGrpcClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V1/KeyManagementServiceClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V1/Gapic/KeyManagementServiceGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1/KeyManagementServiceClientTest.php.
synthtool > Replaced 'CryptoKey_CryptoKeyPurpose' in src/V1/Gapic/KeyManagementServiceGapicClient.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/CryptoKeyVersion_CryptoKeyVersionView.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/CryptoKey_CryptoKeyPurpose.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/CryptoKeyVersion_CryptoKeyVersionState.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/CryptoKeyVersion_CryptoKeyVersionAlgorithm.php.
synthtool > Cleaned up 1 temporary directories.
synthtool > Wrote metadata to synth.metadata.

```
googleapis/google-cloud-php,jdpedrie/google-cloud-php,chingor13/google-cloud-php,googleapis/google-cloud-php,chingor13/google-cloud-php,jdpedrie/google-cloud-php,chingor13/google-cloud-php,googleapis/google-cloud-php,jdpedrie/google-cloud-php