The ResourceTest class provides several functions for defining and
creating a hierarchy of resources encoded into a string array. This
functionality is hard to understand as it uses a default factory method
in the ResourceTest class that may be called by a template method in
ResourceTest and may be overwritten in subclasses. In addition, the
functionality is not used very often.

This change streamlines the functionality for creating resource
hierarchies. It makes the creation explicit where it is required by
inlining the string definitions where possible or implementing the
hierarchy creation in the actual test class rather than relying on the
template method in the ResourceTest superclass. This makes the tests
more independent from their JUnit 3-specific type hierarchy.

Contributes to
https://github.com/eclipse-platform/eclipse.platform/issues/903