Fixtures support in JUnit 5

[gnl42]

As @BeckerFrank noted in #589, fixtures need to be supported in JUnit5.
The problem is that JUnit 5 doesn't have anything equivalent to the TestSuite used in Junit4 to pragmatically create a test suite for each fixture found.

I'm not sure what a good solution would be:

1. Only have one version of each server, ie. not allow multiple fixtures:
   The current multipass setup only has one of each type (should Bugzilla 5 be added to the mix?)

2. Dig into the depths of JUnit5 and come up with a TestSuite framework:
   Not a fan of the idea. Would add complexity to the test support code we don't need.
   And should really live with the JUnit code base, not Mylyn

3. Use something like @MethodSource for all appropriate fixtures:
   Would make for strange reading of the test runs. Possibly mitigated by used the ordered method option

4. Create AllXXXTests suite for each fixture. E.g. AllBugzilla4Tests, AllBugzilla5Tests:
   I can see it using combination of Extensions, Annotations, and maybe ArgumentsProvider for the tests in a class

   Not sure how you would run specific tests against a specific fixture?

5. ???

Comments?

Thanks
George

[BeckerFrank]

I create a POC in branch POC_Junit5_BugzillaRest.