Update MATLAB xunit test framework

[oerc0122]

Herbert's copy of the test framework is currently well behind the new one which has some nice features we may want to use.

Updating the framework may be complicated by the inclusion of skipTest, TestCaseWithSave, assert*WithSave, etc.

These are extensions to the standard xunit.

[ghost]

Is the purpose of this issue to update the xUnit framework we're using? Or move to the inbuilt Matlab framework? For me, the ideal would be the latter, but is also obviously more work as it's a change in syntax for all tests.

Edit:

• Updating the xUnit framework would give us XML reports which would be very useful for https://github.com/pace-neutrons/Horace/issues/527 and would (hopefully) allow us to keep our TestCaseWithSave extensions.
• The Matlab built-in framework provides many more features: XML reports, mocking, coverage reports, parameterized tests, running tests in parallel, performance tests etc.