Apache VHost SetEnv Configuration Option

[seth-reeser]

Per website, develop the ability to set a key-value pair of an Apache environment variable - https://httpd.apache.org/docs/2.4/en/mod/mod_env.html#setenv

This will allow secrets (such as API keys, etc) to be stored in the encrypted configuration file and accessed via PHP.

However, this then forks the website's repo to not be modular, so we really need to validate this approach or come up with something different (encrypted file per website?).