Support registering custom interface modules

[zbarbuto]

Issue Type

• [ ] Bug
• [x] Feature Request
• [x] Improvement

Issue Description

Allow developers to register custom components that can be viewed in the interface.

Completely undecided on the api for this but perhaps either provide a component class in the @DeveloperCategory decorator or done at the root DevmodInterfaceModule import.

This would also allow a few of the current features like observable tracking to become registered modules.