Implement child component routes

[LeStegii]

• Routes should be able to define child routes which contain components to be displayed inside of the main component
• Add a custom javafx element representing the location the child controller will be displayed

Example

  {
    path: ':course',
    component: CreateCourseSolutionsComponent,
    children: [
      {path: 'assignments/:assignment', component: CreateSolutionComponent}
    ]
  }

@Inject
@Route(route = "/course")
@Child(route = "/assignment/:assignment", controller = "createSolution")
CreateCourseSolutionsController createCourseSolutions;

@Inject
CreateSolutionController createSolution;