[Masonry] Move alternate masonry tests into its own folder
See #47635.
Moving new Masonry tests into css/css-masonry.
Bug: 343257585
Change-Id: Ic1692648d73981315f8731f56f3bdc6aee49aa81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5791832
Commit-Queue: Ethan Jimenez ethavar@microsoft.com
Reviewed-by: Alison Maher almaher@microsoft.com
Cr-Commit-Position: refs/heads/main@{#1343091}