Allow for Test test cases to run in parallel

[Badgerati]

Test cases for Tests are currently run sequentially, even if they're in within a parallel repeat. This issue is for the implementation of a [ParallelTestCase] attribute, which will allow all test cases for a Test to be run in parallel.

This will not apply to TestFixtures likewise with parallel repeats, as it will cause sequential only running tests to be forced to run in parallel.

[Badgerati]

There is now a new [ParallelTestCase(<parameters>)] attribute with which to decorate your tests.

ParallelTestCases and TestCases can be combined on tests. ParallelTestCases will all run in parallel first, followed sequentially by normal TestCases.