Use `displayName` on Components and Systems

[fernandojsg]

Similar to what React does, so we don't rely on class.constructor.name anymore as that will get mangled after using uglify it (eg webpack production, parcel, ...)
This will help with serialization #200 and tooling

[fernandojsg]

It could be something like

class Position extends Component {}
Position.displayName = "Position";
Position.schema = {
 /* ... */
};

[fernandojsg]

Already used and added System and Component and getName() to do displayName || constructor name