refs #5614
- change isPublicContext to detectPublicContext
- behaviour now expands the context object out
- this is a bit of a sideeffect, but this is the simplest change
that makes it possible to use the context in the model layer without
significant wider changes
- add new access rules plugin
- takes a context object as part of `forge()` & caches it on the model instance
- provides helper functions for testing access rules later on
