Flatpak already doesn't show the architecture column in the output of
"flatpak list" if every flatpak has the same architecture. This commit
does the same for the table printed for install/update/uninstall
operations, except if the user specifies an arch on the command line.
Fixes https://github.com/flatpak/flatpak/issues/2794Closes: #2930
Approved by: matthiasclasen