[WebGPU] Delete Tools/WebGPUAPIStructure
<rdar://problem/109283183>
Pull request: https://github.com/WebKit/WebKit/pull/13827
Committed 264035@main (90d9f017c6e5): <https://commits.webkit.org/264035@main> Reviewed commits have been landed. Closing PR #13827 and removing active labels.