Two-column modal (forms)

[juanruitina]

Pattern to amend

Modal

Visual

This is the visual @lyubomir-popov did for the form on MicroK8s, here on Figma:

Actual working example: go to https://canonical.com/data/spark and click on "Contact us"

Context

Following the new visual styles, we are using a two column layout for forms within modals. We should define how it should behave.

• The close "x" button should always be visible, at least with the two column layout. Is this ok visually?
• I'm inclined to make only the form scrollable. What happens though if content on the first column is long?
• I think the modal shouldn't have margins on mobile, at least in this use case.

Prompted by @carkod in https://github.com/canonical/canonical.com/pull/1044#issuecomment-1740706457