feat(contacts): add API to address-books, contacts, groups

* full gateway to /carddav
 * add system readonly address-book issued from OxiCloud users

src/interfaces/api/handlers/mod.rs

@@ -5,6 +5,7 @@ pub mod batch_handler;
 pub mod caldav_handler;
 pub mod carddav_handler;
 pub mod chunked_upload_handler;
+pub mod contacts_handler;
 pub mod dedup_handler;
 pub mod device_auth_handler;
 pub mod favorites_handler;