Consolidation with CDI-PIO (develop)

Generally, this is !11 (merged) rebased onto the develop branch.

This is the first develop-based version accepted by the Buildbot of ICON: https://buildbot.dkrz.de/grid?branch=m300488/cdi-pio-2-integration

tests/pio_cksum_grb2.run.in

-#!@SHELL@
+#! @SHELL@
 
 suffix=grb2
 pio_write_args="-w 3"