Memory profile tables should scroll together

When a developer enables "Advanced developer settings" from the general DevTools setting dialog, the Memory panel includes a table that shows GC statistics.

This table is above the memory profile table, and looks like it is part of the memory profile table. However, the two tables are separate, and scroll separately.

We should figure out a way to get them to scroll horizontally together, possibly by adding a `MultiTable` widget that supports multiple tables.

Reproduce the Memory panel with Advanced developer settings enabled and inspect how the GC statistics table and memory profile table are rendered separately. Determine the appropriate shared scrolling or MultiTable approach, then verify that both tables scroll horizontally together without changing their existing content or layout.

Written by the indexing model from the issue text.