Use systemNickname in conversation merger

ts/ConversationController.ts

@@ -601,6 +601,7 @@ export class ConversationController {
                 'profileName',
                 'systemGivenName',
                 'systemFamilyName',
+                'systemNickname',
                 'type',
                 'username',
               ]);

ts/model-types.d.ts

@@ -422,6 +422,8 @@ export type ConversationRenderInfoType = Pick<
   | 'profileFamilyName'
   | 'profileName'
   | 'systemGivenName'
+  | 'systemFamilyName'
+  | 'systemNickname'
   | 'type'
   | 'username'
 >;