[flang] Add NEW_LINE intrinsic to the intrinsic table

NEW_LINE intrinsic folding was already implemented but it had not
yet been added the the intrinsic table and was therefore not yet
recognised an intrinsic.
Add related tests.

Original-commit: flang-compiler/f18@42fcf5b5f1e63267a024afaad39f012982c8abc1
Reviewed-on: https://github.com/flang-compiler/f18/pull/734