[accessibility] Use `<button>` or `<a href="#" role="button">`

[Malvoz]

The <a> print button is not keyboard focusable/operable. Additionally, it is announced as a "link" using a screen reader (missing role="button"). Otherwise <button type="button"> is recommended, but requires additional styling to reset browser defaults.

See related resources:

• https://github.com/Leaflet/Leaflet/blob/bdd7ebf836201550f6d173943b728098b83f40d5/src/control/Control.Zoom.js#L85-L91
• The WAI-ARIA Authoring Practices recommended keyboard interactions for buttons.

[Malvoz]

Other potentially helpful resources:

• Leaflet Guideline: Test your maps
• Leaflet Plugin Authoring Guide: Content Accessibility