Consistent PhET-iO API/assertions for UI component LinkedElements

[zepumph]

#920
#914

• In checkbox we added this code, and think we can factor it out for reuse in radio buttons, slider, combo box, etc:

      // must be after the Checkbox is instrumented
      this.addLinkedElement( property, {
        tandemName: 'property'
      } );
  
      if ( assert && Tandem.VALIDATION && this.isPhetioInstrumented() ) {
        assert && assert( property.isPhetioInstrumented(), 'Property should be instrumented if Checkbox is instrumented' );
  
        if ( this.phetioFeatured ) {
          assert && assert( property.phetioFeatured, `Property should be featured if the controlling Checkbox is featured: ${property.phetioID}` );
        }
      }

• Handle situations like MysteryOrCustomLauncherSection where the UI is fed by an uninstrumented DynamicProperty purposefully.

• Apply the phetioLinkedProperty slider pattern to support things.

[zepumph]

I now see that this issue is most likely a duplicate of #782, but I will work in this issue to make things more clear how we got to this work.