Change modal close + supplementaryButton to md

[RasmusKjeldgaard]

Which issue does this PR close?

This PR closes #2350

What is the new behavior?

The icon for small buttons has been made smaller in #2245.

This means that the modal has unintentionally small buttons now, for the close icon and the supplementary button (e.g. the collapse button for the drawer.

Does this PR introduce a breaking change?

• Yes
• No

Checklist:

The following tasks should be carried out in sequence in order to follow the process of contributing correctly.

Reminders

• Make sure you have implemented tests following the guidelines in: "The good: Test".
• Make sure you have updated the cookbook with examples and showcases (for bug fixes, enhancements & new components).

Review

• Do a self-review.
• Request that the changes are code-reviewed
• Request that the changes are UX reviewed (only necessary if your PR introduces visual changes)

When the pull request has been approved it will be merged to develop by Team Kirby.