IRODS_ENVIRONMENT_FILE should dictate env file path only, never the .irodsA path

[d-w-moore]

The derived_auth_filename free function determines among other things the absolute path where the free functions

• write_pam_credentials_to_secrets_file
• write_native_credentials_to_secrets_file

create a new .irodsA file. Unlike the iCommands' behavior though, with the present PRC v3.0.0 behavior the IRODS_ENVIRONMENT_FILE environment variable can influence where .irodsA file is found/written (ie bends it toward the same directory as the env file read by the session object) in the event that IRODS_AUTHENTICATION_FILE is not defined in the environment.

If we were following the same rules as the iCommands, IRODS_ENVIRONMENT_FILE environment variable would dictate only the location of irods_environment.json is read from, not where .irodsA is read and/or written. In other words, their use should be orthogonal, based on the iCommands' good (and less confusing) example.