[IDEA] Allow configuring admin username and password using environment variables

[aristotelos]

Is your feature request related to a problem? Please describe.
When installing Mirth, one has to manually update the admin password. For deployment automation this is not great.

Describe your use case
My use case is that I want to start Mirth using Docker and set a new secure password (and if possible, username) for the admin user. E.g. CONNECT_ADMIN_PASSWORD and CONNECT_ADMIN_USERNAME.

Describe the solution you'd like
Allow configuring admin username and password using environment variables.

Describe alternatives you've considered
The only alternative for automated deployment is to use HTTP API requests to update the password of the admin user after starting Mirth. I think many users of Docker will not take this extra step and therefore leave the unsecure password - which is a security issue.

Additional context
This feature request is related to #4842 but different in the sense that it is about changing the admin account and not about creating a normal user account. Furthermore, #4842 does not mention deployment automation.

See also nextgenhealthcare/connect-docker#9.

[tonygermano]

It's probably not actually related to #4842. That is for the operating system user used to run the mirth service. The docker container already uses a non-root user to start the server.

I don't think that setting these variables should necessarily change the password for the admin user for an existing install, but should be looked at as initial values when mirth requires generating a new database.