Refactor WebSocket message interfaces

Changes:
- Replace AccountTextMessage with an extendable ContactMessage interface
- Add accountId parameter to server-side WebSocket callbacks
- Set the accountId for WebRTC messages on server-side for security
- Rename all WebRTC and SDP variables to proper camelCase or PascalCase

GitLab: #147
Change-Id: I125b5431821b03ef4d46b751eb1c13830017ccff
diff --git a/common/src/interfaces/websocket-interfaces.ts b/common/src/interfaces/websocket-interfaces.ts
index 2c6a109..c4d6b0b 100644
--- a/common/src/interfaces/websocket-interfaces.ts
+++ b/common/src/interfaces/websocket-interfaces.ts
@@ -17,24 +17,27 @@
  */
 import { Message } from '../Conversation.js';
 
+export interface ContactMessage {
+  contactId: string;
+}
+
 export interface ConversationMessage {
   conversationId: string;
   message: Message;
 }
 
 export interface ConversationView {
-  accountId: string;
   conversationId: string;
 }
 
-export interface WebRtcSdp {
+export interface CallAction extends ContactMessage {
+  conversationId: string;
+}
+
+export interface WebRtcSdp extends ContactMessage {
   sdp: RTCSessionDescriptionInit;
 }
 
-export interface WebRTCIceCandidate {
+export interface WebRtcIceCandidate extends ContactMessage {
   candidate: RTCIceCandidate;
 }
-
-export interface CallBegin {
-  conversationId: string;
-}