Add utilities for safe area

Created by: andreas-web

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

How about extending the spacer classes .p-*, .m-*, .top-* etc. with the safe-area spaces? The values env(safe-area-inset-*) must be used here.

Motivation and context

Mobile devices such as the iPhone or iPad in particular require these spaces. However, it also makes sense that existing spacer classes can override these values. Therefore, the new classes should be integrated into the existing network with great care.