Add learning objectives for Scaling Up Unit Testing

[eirini-zormpa]

• Gutenberg materials
• Carpentry materials

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Learning objectives:

• Use parameterisation to automatically run tests over a set of inputs
• Use code coverage to understand how much of our code is being tested using unit tests

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Notes:

• like in learning objectives for Automated testing #85 this is a copy of the original materials with the same caveats