Rewrite sharing dialog
The current sharing dialog has some problems with the way it interacts with the supported apps (Clocks and Weather), see #51 (closed). Additionally we can't detect the presence of these apps from a Flatpak (at least not with the current code). Instead an idea might be (awaiting an eventual proper "sharing portal") to offer a dialog with option to open the location in a browser (the OSM object's URL) or start composing an e-mail with the URL as the body (and a suitable subject), and maybe additionally a way to manually select and copy the link, or maybe copy it straight to the clipboard. Might register separate bugs for implementing alternatives for time and weather information for places (or alternatively this might be dropped).