Add a SQL schema and DAO for KmsSecretRevision (#840)

* Add a SQL schema and DAO for KmsSecretRevision

The dual-object nature of KmsSecret and KmsSecretRevision will not be
necessary once we have moved to SQL. In that world, the only object will
be the one now called KmsSecretRevision. KmsSecretRevision already
stores its parent so all we need to do is convert that key to the String
secretName (or from the secretName to the key, if loading from SQL) and
select the max revision ID for a given secret name.

In a future PR, we will add a dual-writing DAO to these objects and
perform the dual writes, similar to how ReservedList functions.

* Regenerate diagram

* Rename revisionId and cryptoKeyVersionName

* Fix SQL files and diagram

core/src/main/resources/META-INF/persistence.xml

@@ -62,6 +62,7 @@
     <class>google.registry.model.registry.Registry</class>
     <class>google.registry.model.reporting.DomainTransactionRecord</class>
     <class>google.registry.model.reporting.Spec11ThreatMatch</class>
+    <class>google.registry.model.server.KmsSecretRevision</class>
     <class>google.registry.model.smd.SignedMarkRevocationList</class>
     <class>google.registry.model.tmch.ClaimsListShard</class>
     <class>google.registry.persistence.transaction.TransactionEntity</class>