Small refactor of paternity calculator v2
Small refactor to maternity calculator
Adjustments to paternity calculator flow and test
Update adoption calculator logic and content

- Changes to adoption calculator flow including several new questions.
- New outcomes with additional calculation and leave tables.
- Small adjustments to paternity calculator to accomdate changes needed for calculations.
- Small refactor of maternity calculaotr.
- Additional tests for adoption calculator.
- Small changes to paternity and maternity tests.
- Additional maternity paternity calculator unit tests.
Merge pull request #966 from alphagov/adoption-calculator-update

Adoption calculator update logic and calculations