Hash slotname, if it exceeds 63 characters in streams

[johannesknauft]

The replication slot in Postgres is of type name, which has a char limit of 63. At the moment the inputs of the stream section are used to generate the slot name, they are constructed by combining fes_{dbname}_{app_id}. This easily can exceed 63 characters, as application ids tend to be longer in a microservice environment, and also db names can contain things like team-name, environment, and the same long app-id. To address this when using streams in the Postgres manifest, I created a PR that checks if this is the case and then hashes the slot name to ensure its length is always shorter than 63. This should result in the configuration not failing when applied.

I am also happy to discuss/implement other alternatives like:

• Truncating
• Shortening: long_application_id -> lai