refactor: some restructuring

- move structs inside `sr_tools.rs` into individual file
- implement in-game equip handler (relic & lightcone)

gameserver/src/net/packet.rs

@@ -190,6 +190,7 @@ trait_handler! {
     TakeOffEquipment;
     DressRelicAvatar;
     TakeOffRelic;
+    RankUpAvatar;
 
     // Chat (dummy!)
     SendMsg;