Eli 782/add constant and field for configurable status text

[oneeb-nhs]

Description

Context

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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[eddalmond1]

I think it's worth amending test_matched_action_detail_existing_constructor_still_works_with_three_args and test_matched_action_detail_existing_constructor_works_with_four_args to use hamcrest, the other new tests are simpler, but would be quick to amend them too