Add support for External Module fixtures - CDISC, Dictionaries, Import Files

[aldefouw]

Need to expand support of EM fixtures to also support Dictionaries and Import Files.

Currently limited to only CDISC implementations, but we can use the CDISC support to inform how to approach Dictionaries and Imports Files.

Will need additional adjustment to https://github.com/vanderbilt-redcap/rctf/blob/main/commands/data_import.js.

[mmcev106]

@aldefouw, if you can provide an examples of steps that is are not working as you'd expect, I can likely make them work.