scripts/qemu-ga-client: apply (most) pylint rules

scripts/qemu-ga-client: apply (most) pylint rules

I'm only doing a very quick best-effort to preserve this script, to help
keep it from breaking further. I think there are pending ideas swirling
on the right way to implement better SDKs and better clients, and this
script might be a handy reference for those discussions. It presents
some interesting design problems, like static type safety when using a
dynamic RPC mechanism.

I believe it's worth preserving the effort and care that went into
making this script by updating it to work with our current
infrastructure. However, I am disabling the requirement for docstrings
in this file.

If you would like to help improve this script, please add docstrings
alongside any refactors or rejuvenations you might apply at that time.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210604155532.1499282-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>