Add tests for prompt display based on flag input during init

[cartogram]

WHY are these changes introduced?

This adds more test coverage on displaying prompts in the CLI. We show specific prompts based on what the user passes in as flags, for example, if they pass --template we don't need to ask them what template they want. There were some issues around this recently, which turned out to be malformed user input, but as I was investigating these issues I starting writing tests that should have been here from the start.

WHAT is this pull request doing?

These are pretty repetitive so opted to use a describe.each that iterates over each potential flag. There is a test for when the prompt is displayed (value is omitted), and another to assert that no prompt is displayed (when we receive that flag/option).

HOW to test your changes?

Green CI.

Post-merge steps

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[frandiox]

Thanks Matt!