[Feature request] Don't show the URL preview image when the network is not available
Request: When _hasNetwork() returns false, don't create an URL preview box, because it takes up a lot of space, and does not show meaningful content.
I've found the code here: https://sources.debian.org/src/polari/41.0-2/src/urlPreview.js/
To reproduce: mark your network connection as metered and request a URL in polari.