Id and Entity extension generator

[BeanCheeseBurrito]

This PR implements code generators for adding entity/id method extensions to Alert , Component , Observer , Pipeline , System, TimerEntity , and UntypedComponent . Previously, accessing entity and id methods had to be done through the .Entity and .Id properties.

world.Component<Phases.Render>().Entity
    .Add(Ecs.Phase)
    .DependsOn(Ecs.OnUpdate);

Now entity and id methods can be accessed directly from entity-based objects.

world.Component<Phases.Render>()
    .Add(Ecs.Phase)
    .DependsOn(Ecs.OnUpdate);

Tests and examples have been updated to use the short-form versions.