Append the specified move-insertable value to the back of this queue. value is left in a valid but unspecified state. Return 0 on success, and a non-zero value otherwise. Specifically, return e_SUCCESS on success, e_DISABLED if isPushBackDisabled(), e_FULL if !isPushBackDisabled() and the queue was full, and e_FAILED if an error occurs. On failure, value is not changed.