created a basic user importer class with tests

[spottseng]

Summary

Provide a brief summary of the changes in this PR and link to the relevant issue(s) if applicable.
Creates the setup for the UserImporter class with unit tests. Also does some additional clean up.

Current Behavior

Please describe the current behavior that you are modifying.
No changes.

New Behavior

Please describe the behavior or changes that are being added by this PR.
No changes.

Does this new change introduce a breaking change?

• Yes
• No

If this introduces a breaking change:

1. Describe the impact on the application below.
2. Update the BREAKING.md file with the breaking change.
3. Add "BREAKING CHANGE: [...]" to the commit description when merging.
4. Create a ticket on the GitHub Project board to address the issue later.

Other Information

Any other information that is useful to note: visual changes, dependency changes, etc.