Bug 1924561 [wpt PR 48602] - WebNN: Implement scatterElements opera…

…tor in DirectML backend, a=testonly

Automatic update from web-platform-tests
WebNN: Implement `scatterElements` operator in DirectML backend

The `scatterElements` operator is proposed by WebML WG [1] for
supporting popular transformer-based models.

This CL adds the IDL and mojo definitions of scatterElements, and
implements it in the DirectML backend by mapping to
`DML_OPERATOR_SCATTER` [2].

This CL also adds the `scatterElements` validation and conformance tests
into WPT.

[1]: webmachinelearning/webnn#375 (comment)
[2]: https://learn.microsoft.com/en-us/windows/win32/api/directml/ns-directml-dml_scatter_operator_desc

Bug: 370536101,370538328
Change-Id: Ifb73bed5eb05cb919b106b4aaea5127ec099edb2
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/+/5921136
Reviewed-by: Alex Gough <ajgochromium.org>
Reviewed-by: Weizhong Xia <weizhonggoogle.com>
Auto-Submit: ningxin hu <ningxin.huintel.com>
Commit-Queue: ningxin hu <ningxin.huintel.com>
Commit-Queue: Weizhong Xia <weizhonggoogle.com>
Reviewed-by: Rafael Cintron <rafael.cintronmicrosoft.com>
Reviewed-by: Austin Sullivan <asullychromium.org>
Cr-Commit-Position: refs/heads/main{#1368312}

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wpt-commits: 59751055ef506c581da667594a2da8dac0c599b3
wpt-pr: 48602

UltraBlame original commit: 442931e42d208661100d2921a200317ef2e5e110