merge_pr_49977

webnn: add more gru tests

Add coverage for reset_after=true and bidirection cases.
Increase ULP to 6 for bidirectional.

Bug: 360052663
Change-Id: Ic488a211625b8d74be7242412af631fb65cc0698
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5991963
Reviewed-by: ningxin hu [email protected]
Commit-Queue: Phillis Tang [email protected]
Cr-Commit-Position: refs/heads/main@{#1403673}