webnn: implement where on Coreml
Implement where builder method. Also update utils.js to allow testing
with unsupported input data type by inserting a cast in front.
Bug: 41481333
Change-Id: I12c0d159d3b72f1cdf348417a173d00d908a89d8
Cq-Include-Trybots: luci.chromium.try:win11-blink-rel,mac14.arm64-blink-rel,mac14-blink-rel, linux-blink-rel
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5709541
Reviewed-by: Reilly Grant reillyg@chromium.org
Commit-Queue: Phillis Tang phillis@chromium.org
Cr-Commit-Position: refs/heads/main@{#1329248}