* `l1_norm` error message enhancement

test=develop

* `norm` error message enhancement

test=develop

* `squared_l2_norm` error message enhancement

test=develop

* `squared_l2_distance` error message enhancement

test=develop

* `conv_shift_op` error message enhancement

test=develop

* `sample_logits_op` error message enhancement

test=develop

* Fix format

test=develop

* use `PADDLE_ENFORCE_EQ` for '||' conditional

test=develop

* Fix string format

test=develop

* Add test for `sample_logits`

test=develop

* Add error message

test=develop

* Use ordered dict for outputs

test=develop

* Hard code fetch list so that order is deterministic

test=develop

* Fix license header year

test=develop