Add kitsune-derive and use it throughout the project

[aumetra]

Closes #414

In order to generally decrease the amount of memory used, we can use more Arcs.
That way we only ever have a guaranteed size of 8 bytes per service handle, and a size overhead of 16 bytes per instance (because 1 pointer, 1 atomic counter).

To simplify that implementation and to keep the neat names, this PR adds an attribute macro called kitsune_service which renames the struct, creates a new struct in its place which has one field, an triomphe::Arc which wraps the actual service implementation, and implements Deref, to all the struct fields can be accessed as-is.

In general, I hope this decreases the overall size of the state and maybe memory usage in general.