GcpKmsClient constructor fails silently

[jason-callaway]

If the GcpKmsClient constructor fails, it raises tink.core.TinkError but does not say why it's failing.

For example, if the KMS URI is wrong, i.e., projects/my-project/locations/us-central1/keyRings/my-keyring/cryptoKeys/my-key vs gcp-kms://projects/my-project/locations/us-central1/keyRings/my-keyring/cryptoKeys/my-key, the error that's raised isn't helpful.