[bug#72822] gnu: josm: Update to 19160.

[Julien Lepiller]

Hi Guix!

this small patch series updates JOSM to the latest version. This
requires an update to jmapviewer, whose development stopped in 2022. It
is now maintained by JOSM developpers, hence the source change.

The new version had an issue when starting, where it was not able to
load projections. This is because the generate-epsg phase failed
silently. Creating another empty file was enough (not just renaming the
file, as only one empty file failed differently). When starting, it
showed a message asking to add some options to the java command line,
which I did in this patch.