[Masonry] move shared helpers to grid_layout_utils

This CL moves shared helpers to grid_layout_utils from grid so they
can be reused in the upcoming grid-lanes baseline alignment work.
No behavior changes expected.

Bug: 343257585
Change-Id: I3f8bf3c19f693d6d70b9bd1801847984180a873f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7485457
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Kurt Catti-Schmidt <kschmi@microsoft.com>
Reviewed-by: Alison Maher <almaher@microsoft.com>
Commit-Queue: Yanling Wang <yanlingwang@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1570654}