Make `idle_in_transaction_session_timeout` a configurable setting in databases for postgres

Real life scenario

1. application has a bug that causes a DB transaction to never be closed

2. postgres needs to keep old tuple versions for as long the transction is open

3. autovaccum can't delete old tuples

4. tables start to get bloated

5. performance degrades

This could be mitigated by setting idle_in_transaction_session_timeout to a reasonable value (e.g., 4h - value obviously depends on specific workloads), however that setting is not currently configurable in "Databases for Postgres"