Command to Assign Model(s) to an AnalysisProject

It has been requested that a command be created to manually attach a model to an analysis project.

For consolation the creation of the bridge entity triggers a Timeline::Event so it is possible to determine later that the model was not actually a creation of that analysis project.
I believe the changes I've made create a more useful restriction on linking models to analysis projects than a per-class limitation.  The ease of separating out the manually added models may mitigate concerns about arbitrary model types being added to the projects.

If the consensus is still to limit to those two classes that's easy enough to add in as well!