Granular Derived topics

[devagrawal09]

Our version of solid's createProjection.
Requires #2 and #3

Allow passing a function into createTopic that can attach event handlers that emit into the topic.

const [nextTopic] = createTopic((emit) => {
  onTodoAdded((todoAdded) => {
    emit("Added", todoAdded.id, todoAdded);
  });
});