Implement 'Search test methods' in the Scala JUnit4 test runner.

Hook into the JUnit test configuration tab and implement the
Search Methods button functionality. We use aspects to intercept
the right call, and route it to our `ITestKind` implementation.

Fixed #1001474
Merge pull request #318 from dragos/issue/junit-search-methods-1001474

Implement 'Search test methods' in the Scala JUnit4 test runner.