Create conversations API routes

Changes:
- Create new conversationRouter with routes for conversations
- Add conversation-related methods to Jamid
- Use Message interface over Record<string, string>
- Add return type annotations for functions in Jamid
- Simplify returned value for account creation/registration

GitLab: #95
Change-Id: Ib0af8b60a92d08ddf4843f874c811e4ead870174
diff --git a/common/src/Conversation.ts b/common/src/Conversation.ts
index 5776c59..a1b03da 100644
--- a/common/src/Conversation.ts
+++ b/common/src/Conversation.ts
@@ -25,7 +25,7 @@
 
 type ConversationInfos = Record<string, unknown>;
 
-export type Message = {
+export interface Message {
   id: string;
   author: string;
   timestamp: string;
@@ -44,7 +44,7 @@
   duration?: string;
   to?: string;
   invited?: string;
-};
+}
 
 type ConversationRequest = PromiseExecutor<Message[]>;