feat(core): implement channel unreads model

closes #269

crates/core/models/src/v0/mod.rs

@@ -1,5 +1,6 @@
 mod bots;
 mod channel_invites;
+mod channel_unreads;
 mod channel_webhooks;
 mod channels;
 mod files;
@@ -9,6 +10,7 @@ mod users;
 
 pub use bots::*;
 pub use channel_invites::*;
+pub use channel_unreads::*;
 pub use channel_webhooks::*;
 pub use channels::*;
 pub use files::*;