Add ability to indirectly cover one test from another

[sspeiche]

Currently DirectContainerTest::testActAsIfInsertedContentRelationTripleExists just calls DirectContainerTest::testPostResourceUpdatesTriples.

Instead of just running the same test twice, it would be better to list out the other tests that cover this test/requirement like is done with @coveredByTests though that takes as an arg an array of Classes. Instead it would need to take array of Methods but that isn't allowed so Method names is next best.