ContextServiceTest: test missing service behavior

Specifically, it should not be possible to instantiate a context
requiring a missing service, either directly or transitively.
Inject context and service parameters
ContextServiceTest: add @Parameter injection tests

We want to make sure that *any* class which has @Parameters of type
org.scijava.service.Service or org.scijava.Context has those parameters
populated with the context's associated values, when
Context#inject(Object) is called on it. We also want to make sure that
*if* the object implements the Contextual interface, the result is
exactly the same when calling Contextual#setContext(Context).