PageHeader: Update to support `@mdi/js`

Created by: umpox

Description

Updates PageHeader component to support @mdi/js.

This PR also acts as an implementation guide for future work that we can't yet automatically migrate away from @mdi/js for yet

Test plan

Checked locally through sg start web-standalone. Visual tests

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.