storcon: add safekeeper list API (#10089)

This adds an API to the storage controller to list safekeepers
registered to it.

This PR does a `diesel print-schema > storage_controller/src/schema.rs`
because of an inconsistency between up.sql and schema.rs, introduced by
[this](2c142f14f7)
commit, so there is some updates of `schema.rs` due to that. As a
followup to this, we should maybe think about running `diesel
print-schema` in CI.

Part of #9981

storage_controller/src/service.rs

@@ -7185,6 +7185,12 @@ impl Service {
         global_observed
     }
 
+    pub(crate) async fn safekeepers_list(
+        &self,
+    ) -> Result<Vec<crate::persistence::SafekeeperPersistence>, DatabaseError> {
+        self.persistence.list_safekeepers().await
+    }
+
     pub(crate) async fn get_safekeeper(
         &self,
         id: i64,