This is only used for displaying locations. When previewing/sending a
location, it is assumed to be valid, so no error overlay is necessary.
* Pass a `GeoUri` object to the `LoctionViewer` and `MediaContentViewer`
instead of a geo URI string so it is known to be valid
* Wrap the `LocationViewer` component in a `GtkOverlay` in the
`ContentMessageLocation` component that can overlay an error message
over the location viewer if coordinate parsing fails