Add two new gRPC methods to the SA:
- `RevokeCertByKey` will be used when the API request was signed by the
certificate's keypair, rather than a Subscriber keypair. If the
request is for reason `keyCompromise`, it will ensure that the key is
added to the blocked keys table, and will attempt to "re-revoke" a
certificate that was already revoked for some other reason.
- `RevokeCertByApplicant` supports both the path where the original
subscriber or another account which has proven control over all of the
identifier in the certificate requests revocation via the API. It does
not allow the requested reason to be `keyCompromise`, as these
requests do not represent a demonstration of key compromise.
In addition, add a new feature flag `MozRevocationReasons` which
controls the behavior of these new methods. If the flag is not set, they
behave like they have historically (see above). If the flag is set to true,
then the new methods enforce the upcoming Mozilla policies around
revocation reasons, namely:
- Only the original Subscriber can choose the revocation reason; other
clients will get a set reason code based on the method of requesting
revocation. When the original Subscriber requests reason
`keyCompromise`, this request will be honored, but the key will not be
blocked and other certificates with that key will not also be revoked.
- Revocations signed with the certificate key will always get reason
`keyCompromise`, because we do not know who is sending the request and
therefore must assume that the use of the key in this way represents
compromise. Because these requests will always be fore reason
`keyCompromise`, they will always be added to the blocked keys table
and they will always attempt "re-revocation".
- Revocations authorized via control of all names in the cert will
always get reason `cessationOfOperation`, which is to be used when the
original Subscriber does not control all names in the certificate
anymore.
Finally, update the existing `AdministrativelyRevokeCertificate` method
to use the new helper functions shared by the two new methods.
Part of #5936
07d56e3772