Provide a component scanner utility

[utybo]

Many Tegral DI plugins rely on the following process:

• Scanning the existing components
• Register them in one way or another in an internal map.
• At a later point, retrieve all the components and call something on them

Example of such plugins include Tegral DI's services feature and Tegral Web Controllers' controller and module detection feature. I'm pretty sure this functionality could be refactored into a "component scanner" class which plugins could instantiate and/or configure.