Support editing components

[randomPoison]

This issue references work that is in ticket #26. It isn't fully blocked by that ticket, but it might be easier to do once #26 is finished.

Following the examples set for #25 and #26 we should also add support for editing components. The following things need to be done to enable such support:

• Add a new variant to IncomingMessage called ComponentUpdate that contains the ID for the component type, the entity the component is attached to (as a SerializableEntity), and the data for the component (as a serde_json::Value).
• Rename SyncComponentSystem to ReadComponentSystem and move it into it's own read_component module.
• Make a new System WriteComponentSystem mirroring WriteResourceSystem and put it in a new write_component module.
• Rename ComponentSet to ReadComponentSet.
• Add a new trait WriteComponentSet in the type_set module mirroring the WriteResourceSet trait (which should be created for Register read-only resources #26).
• Rename SyncEditorSystem::deserializer_map to resource_deserializer_map and update SyncEditorBundle accordingly.
• Add a member component_deserializer_map to SyncEditorSystem that mirrors resource_deserializer_map. It should take the Component ID (i.e. the name used when registering the component) and map it to a Sender<(Entity, serde_json::Value)>. The corresponding WriteComponentSystem should have the Receiver end of the channel.
• Update SyncComponentBundle::sync_component and sync_components to require that the registered types be Serialize + DeserializeOwned (or ReadComponentSet + WriteComponentSet in the case of sync_components.
• Add methods read_component and read_components to SyncComponentsBundle that only require the types to be Serialize/ReadComponentSet.

Note that these steps assume that #26 has been completed. If this is being done before #26, you can still follow all the steps here, however you may need read #26 to understand the details for how to support read-only components (i.e. needing both a ReadComponentSet and a WriteComponentSet trait).

I'm happy to answer any questions or offer mentorship for anyone who wants to take on this task 🙂