Config file error checker and config management

[liquidsteves]

One pain point for new users running ELSA locally for the first time is correctly filling in config variables: .env files, ssh credentials, and serge configs.

We could make this easier with config file verifier logic which:

• Tells you if all variables are filled out in a valid way
• Suggests how to fill out variables you are missing. (This would also alert you if a new required variable is added and you need to update your file)
• Alerts you to syntax gray areas that may be parsed differently by different libraries (eg spaces, newlines for .env files)
• Tests all the login credentials to make sure they work

Relatedly, supporting multi-tenancy (as Justin mentioned) from a single administrator means automatically toggling between different sets of config files. Should we make that easier?

Should we put more thought into hierarchies of config files, inheriting from and overriding each other?