Support passing workingDirectory token in platform context

Ui-testing's test-module.js can process a --run option like this:

--run WD/checkin/checkout/users/inventory/requests/circulation/organization

However the same option passed through stripes-cli's stripes test nightmare command fails.

The CLI is expecting --run to reference an app script name and thus prefixing the option with "WD" to run a given script in the app context's working directory. This prefix needs to be assigned only under specific conditions: app context, or... ?