Include webmonetization header if pod owner has a payment pointer

[michielbdejong]

If the pod owner (Alice) has configured a payment pointer through https://github.com/solid/solid-panes/issues/273 then it makes sense that the html hosted on her pod includes a web monetization header. That way, if someone else (Bob) browses the content of Alice's pod through on-pod Solid OS, Alice will be able to monetize her pod content.