flux-ion-resource: move to src/cmd and install

problem: recent production debugging and fixes have benefitted from
having flux ion-resource available, but it is not installed.

solution: install it, and since it's no longer a test-only script, move
it to src/cmd/

Author: trws

src/cmd/CMakeLists.txt

@@ -1,3 +1,4 @@
 # TODO: install flux-ion-R command
 install(PROGRAMS flux-ion-R.py
+  flux-ion-resource.py
   DESTINATION ${FLUX_CMD_DIR})