MM-53228: Adding schema version to cluster info (#24209)

With the schema version available, a job can query for
the cluster info to confirm whether or not all nodes
in a cluster are upgraded to the same version or not.

This will help it in determining whether to start
the job or not.

https://mattermost.atlassian.net/browse/MM-53228

```release-note
NONE
```

webapp/platform/types/src/admin.ts

@@ -70,6 +70,7 @@ export type ClusterInfo = {
     config_hash: string;
     ipaddress: string;
     hostname: string;
+    schema_version: string;
 };
 
 export type AnalyticsRow = {