sxmo/*: upgrade to sxmo 1.2.0

This is a major update of the Simple X Mobile environment, upgrading various packages. Upstream ticket: https://todo.sr.ht/~mil/sxmo-tickets/110 .

• sxmo-xdm-config is a new package, replacing sxmo-xdm, which is removed now
• sxmo-svkbd is removed, instead svkbd is used (provided by Alpine)

The merge for this should be timed to coincide with that of dependency lisgd in Alpine: https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/15323