Workspaces can be pinned, and dragged to reorder or move to a different
output.
These features are enabled only if cosmic-workspace-v2 advertises the
necessary protocol version and capabilities.
The layout of the labels and pin buttons could be tweaked a bit still.
Some hacks and workarounds are needed to get drag and drop working as
desired. Something iced and libcosmic could potentially improve in the
future. But this now seems fairly robust.
