Platoons social functionality (#91)

### Description

This implements and completes #87 (to the best of my knowledge)

### Game

Robocraft

### Please confirm

- [x] I am the legal owner or represent the owner of all work submitted
- [x] I consent to my submission being added to this FOSS project
- [ ] This PR used LLMs to generate some or all of the code changes

Reviewed-on: https://git.ngram.ca/OpenJam/rc-servers/pulls/91
Co-authored-by: NG (Graham) <ngniusness@gmail.com>
Co-committed-by: NG (Graham) <ngniusness@gmail.com>

rc_lobby_room/src/events/battle_enter.rs

@@ -30,6 +30,7 @@ impl BattleEnter {
     fn as_transmissible<C>(&self) -> Vec<(u8, polariton::operation::Typed<C>)> {
         let player_datas = polariton::operation::Typed::Arr(polariton::operation::Arr {
             ty: polariton::serdes::TypePrefix::HashMap,
+            custom_ty: None,
             items: self.player_datas.iter().map(|x| x.as_transmissible()).collect()
         });
         let mut vec = Vec::with_capacity(11);