This diff updates the `Modal` component to follow the new style rules outlined by Ted in his web app redesign. The rules for the redesigned modals are outlined below
- New modals will include an “button section” that will be present in all modals that need buttons.
- The button section will always live on the bottom of the modal, and contain all the buttons needed.
- If there is only one button for the modal, then the button will fill up the entire space of the section with 32px on the sides and 16px top/bottom.
- All modals should have a 32px margin on the top and sides.
Here are some screenshots from the figma that help provide context for how the new modals should look visually
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Here is another example from Figma better showing what the button section looks like (has a different shade of black for the background)
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> Please note that this diff will cause a bunch of regressions to our modals since pretty much all of our modals have their own one off spacing styles + buttons. This diff and subsequent diffs will not be landed until all modals are ready to be landed.
This diff just focuses on the new uniformed spacing + introducing the button container (with support for only a primary button). Subsequent diffs will handle extending the modal component props API to have support for secondary buttons, danger buttons, subheaders, etc.
Linear task: https://linear.app/comm/issue/ENG-5943/extendmodify-the-modal-props-api-to-follow-new-modal-designs