This patch rework "network delete" command following the
rules in doc/source/command-errors.rst.
In "network delete" command, there are multiple REST API
calls, and we should make as many of them as possible.
And log error for each one, give a better error message.
Also return a non-zero exit code.
Change-Id: I39ae087dd7bd08d049d513abfa6c5cab2bd13b2b
Partial-Bug: #1556719