Integrate ReplicationConnection with NpgsqlDataSource #5692

The issue

I have logical replication user which gets its password regularly rotated. For normal connections, this kind of setup is well supported via UsePeriodicPasswordProvider, but replication connections require a raw connection string at construction.

From a quick look through the source, it looks like ReplicationConnection (and therefore LogicalReplicationConnection) directly constructs a NpgsqlConnection in its constructor. As far as I'm aware, this means we cannot use the existing password provider or periodic password provider infrastructure for injecting dynamic secrets into logical replication connections.

Is it possible to change ReplicationConnection to support this?