Simplify Measure Condition rendering

This change is for https://www.pivotaltracker.com/story/show/61986128

The error was introduced with changes for public API, when formatters were moved to the backend.

We used to present Measure Conditions like the old tariff did. This change alter that and displays them the same way EU TARIC does. It is not a significant change, all information is still there. As a result the code is simpler - less logic involved.

I added more test cases to Tariff Suite: https://github.com/alphagov/trade-tariff-backend/pull/132