This change exludes internal and nested types from being treated as
controllers. This is consistent with MVC5's behavior.
DefaultActionSelectionConventions was primarily tested through running
action selection. I wanted to also test the methods with substantial logic
in this class, so I moved a spate of a classes from private classes inside of the
integration tests to public classes so they could be shared. I also added
tests to fill gaps in DefaultActionSelectionConventions, which is the vast
vast majority of this change.
The default implementation has a safe race, and does not allow for action description addition at runtime.
It can be replaced with an implementation that can reload.
Consumers of the new service that do extra caching are now responsible to look at the version and change the implementation.