Add options to enable and configure metrics.
See ENABLE_METRICS='false' or if you want 'true' and METRICS_OPTIONS.

As if you enable metrics, they will be enabled for prometheus to be served on port 9930

Introduce the usage of config.json to define db credentials.
This is not backwards compatible.

To 2.36.0

See merge request !4

To 2.33.0

See merge request !3

- set individual postgresql.conf