Apply `grid` module to interactive layout(s)

This came up while working on #15123. It would be an awful lot easier to handle full width elements and the occasional DOM manipulation on interactive pieces if the grid layout of the template spanned the full viewport width. Then stuff like `fullWidth` weighting would be a CSS-friendly one-liner rather than a bunch of negative left margins.

As with most things interactives related this potentially opens a can of worms. Even if we can successfully update the templates to use the `grid` module, will old atoms work or will they break horribly? Would we need a before/after fork? And what kind of precedent would that set?

One to explore.

Alternative thought: make [revamped `StandardLayout`](https://github.com/guardian/dotcom-rendering/pull/15428) the new interactive layout?

## Context and useful links

- https://github.com/guardian/dotcom-rendering/pull/3626