Assign unique color indices to room participants, use those instead of replica_ids

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Antonio <antonio@zed.dev>

crates/call/src/participant.rs

@@ -6,6 +6,7 @@ pub use live_kit_client::Frame;
 use live_kit_client::RemoteAudioTrack;
 use project::Project;
 use std::{fmt, sync::Arc};
+use theme::ColorIndex;
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum ParticipantLocation {
@@ -43,6 +44,7 @@ pub struct RemoteParticipant {
     pub peer_id: proto::PeerId,
     pub projects: Vec<proto::ParticipantProject>,
     pub location: ParticipantLocation,
+    pub color_index: ColorIndex,
     pub muted: bool,
     pub speaking: bool,
     pub video_tracks: HashMap<live_kit_client::Sid, Arc<RemoteVideoTrack>>,