[Feature]: Config output_dir does not behave as expected

[jprokos26]

1. When supplying a value such as INTL as output_dir, armory outputs the results to ~/.armory/outputs/INTL_<generated_name>/… as opposed to what would be expected ~/.armory/outputs/INTL/<generated_name>/…
2. When supplying an absolute path to output_dir it throws a Permission denied error, if armory should still throw an error here, it might be useful to update the error message to inform the user that output_dir should be a relative path.

NOTE: Can supply INTL/ as the output_dir to have it output in that folder as a no-code-change fix

[christopherwoodall]

There is a lot of directory management/creation logic happening in armory/scenarios/scenario.py and also armory/paths.py.

I like the idea of consolidating all of the directory creation logic inside paths.py but am curious about what others think.

[swsuggs]

Related to #1329. I agree if the output dir and filename values are supplied, Armory should not append the timestamps and IDs. @christopherwoodall Feel free to consolidate the logic in a way that makes sense to you if you are still interested in taking care of this