[Feature request]: Add support for OPENVOXDB_POSTGRES_PASSWORD_FILE env var

[mdechiaro]

Use Case

This environment varable would support secrets in a docker compose setup. The postgres container and puppetdb container can share the secret for ease of use. Here is an example config:

---
services:
  postgres:
    environment:
      POSTGRES_PASSWORD_FILE: "/run/secrets/db_password"
    secrets:
    - db_password
  puppetdb:
    environment:
      OPENVOXDB_POSTGRES_PASSWORD_FILE: "/run/secrets/db_password"
    secrets:
    - db_password
secrets:
  db_password:
    file: "/path/to/db_password"

Describe the solution you would like

A shell function would need to be added docker-entrypoint.d that can read /run/secrets/db_password and set OPENVOXDB_POSTGRES_PASSWORD with the password.

Describe alternatives you've considered

No response

Additional context

The postgres image supports this _FILE feature with the following variables. For this request, I believe the password env var is most important.

POSTGRES_INITDB_ARGS
POSTGRES_PASSWORD
POSTGRES_USER
POSTGRES_DB