The user configuration directory can be overridden via environment
variables or configuration files.
In the current implementation `Msf::Config.config_directory` should be
utilized for consistent location reporting. `Msf::Config.get_config_root`
is reserved to generation of a default location and should be considered
`private` as it ignores some injected configuration options. Currently
autoloading does not allow application of the `private` keyword to this method,
requiring guidance during development that module writers should access the
full configured `user` value of `Msf::Config.config_directory`.
Grant Willcox