feat(NODE-4795) deprecate addUser on db

Author: durran

src/db.ts

@@ -405,6 +405,7 @@ export class Db {
    * @param username - The username for the new user
    * @param passwordOrOptions - An optional password for the new user, or the options for the command
    * @param options - Optional settings for the command
+   * @deprecated Use the createUser command directly instead.
    */
   async addUser(
     username: string,