Create a different key pr environment about halite

[paragonie-security]

https://github.com/paragonie/halite/blob/master/doc/Classes/KeyFactory.md#loadauthenticationkey

You can load a key from a file. You can use environment variables to tell Halite which suffix to apply in the code that calls this. We aren't building the glue for this into Halite, of course.

[christianostrem]

We found a way around it by using environment ( %env()% ) variables in the halite config path.
Though a .halite.prod environment support would have been great.

[paragonie-security]

Though a .halite.prod environment support would have been great.

We're not opposed to that feature existing. We just don't think it belongs inside Halite.

For frameworks that do a lot of heavy lifting with environment variables, a separate meta-package that wraps Halite is more appropriate than us adding more cruft, technical debt, and attack surface to this cryptography library.