Add project selection options

I anticipate that it will be common to want to work on one project at a time, and in #10 I added a function to get a list of project directories to use as input to the workflow. We should extend that to allow selection of individual projects for test runs, etc.

I expect that this will be partially implemented as an argument to the `Utils.getProjects()` function.

Start by reading issue #10 and the Utils.getProjects() function, including how its project-directory list is passed into the workflow. Determine the expected argument for selecting individual projects and verify that selected projects are the only ones used for test runs and other workflow steps.

Written by the indexing model from the issue text.