Activation: QI-381 Activators are now injectables

Activators can be assembled on Structure (Application, Layers, Modules)
and Services.
Activators assembled on Structure are NOT injectables.

@Structure, @Service and @Uses injections are tested.

Activators are now part of the Application visitable hierarchy.
Code in tools/model-detail is enhanced to provide Activators details.

Most of the changes, code-wise, are in model-details.