Add paths to types in server and service macros

[petekubiak]

gatt_server and gatt_service proc macros can now be used without having to add use trouble_host::prelude::*

Closes #245 .

[petekubiak]

/test

[lulf]

LGTM! I think another improvement would be to use '::trouble_host::...(with the::` prefix), which ensures that it will not be confused if someone adds a mod trouble_host{} in their project.

But I think that's highly unlikely :)

[ivmarkov]

Keep in mind that the current approach does not support crate renaming.

[ivmarkov]

We use this guy in rs-matter: https://docs.rs/proc-macro-crate/latest/proc_macro_crate/