webnn: Migrate split validation tests to WPTs
This CL adds WPT tests for split and removes the unit tests
MLGraphBuilderTest.SplitTest, MLGraphTestMojo.SplitTest and
MLGraphTest.SplitTest.
Bug: 327337526, 328026885
Change-Id: I242743837b6aeba6843a3e6a21d160ea7b2bae34
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5489419
Reviewed-by: Austin Sullivan asully@chromium.org
Reviewed-by: ningxin hu ningxin.hu@intel.com
Commit-Queue: Shanxing Mei shanxing.mei@intel.com
Cr-Commit-Position: refs/heads/main@{#1294100}