Rich text links support for Leaflet shares #14

Since you've already got a rich text editor and support @ and linkified links, also support rich-text links in your share to composer.

e.g. When I do a share when publishing, I want to be able to highlight text and link it. e.g. "As well as this write up, check out this cool website". I'd highlight check out this cool website and add a link to "https://example.com", which would then post as a rich text link.

The composer itself would be an amazing component to extract perhaps?