Run prettier and check tslint on entire codebase

Mainly to run these checks for the recent pull requests.

backend/src/data/GuildReminders.ts

@@ -41,7 +41,7 @@ export class GuildReminders extends BaseGuildRepository {
       channel_id: channelId,
       remind_at: remindAt,
       body,
-      created_at
+      created_at,
     });
   }
 }