webnn: add IDL and mojo definition of gatherElements
This CL also implements validation tests in WPT and corresponding
opSupportLimits.
webmachinelearning/webnn#375 (comment)
Bug: 40206287
Change-Id: Icf24af90830a5b1cd4c96bc46983ea6854bdecab
Cq-Include-Trybots: luci.chromium.try:win11-blink-rel, mac14.arm64-blink-rel, mac14-blink-rel, mac15.arm64-blink-rel, mac15-blink-rel, linux-blink-rel
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5807468
Reviewed-by: Alex Gough ajgo@chromium.org
Reviewed-by: ningxin hu ningxin.hu@intel.com
Reviewed-by: Weizhong Xia weizhong@google.com
Reviewed-by: Rafael Cintron rafael.cintron@microsoft.com
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Cr-Commit-Position: refs/heads/main@{#1347783}