CP-41819: Update except and print() syntax to Python3, use logging

[bernhardkaindl]

TLDR: I expect a review of this PR to take maybe 2-3 minutes or so, it's really short and easy:

The only change that is only obvious by reviewing each commit by commit is this change:

    if k in ['-d', '--debug']:
       dbg = True
+      logging.getLogger().setLevel(logging.DEBUG)  # Activates logging.debug("log messages")
...
From:
-   if dbg:
-      print(...., file=sys.stderr)
-      for (...):
-          print(...., file=sys.stderr)
To:
+   debug(....)
+   for (...):
+       debug(....)   # (Logging default to stderr)

It should be clear - if not preferred, I can remove the last one or two commits.

---

2nd Pull request for the Python3 migration of xenserver-status-report: - Updates the except and print() syntax to support Python3 - Updates the prints to `stderr` to use `logging` or more readable code.

It is split into 5 incremental commits with each commit making one dedicated step of the updates:

git log -n5 --oneline |tac
e11a306 CP-41819: Update except syntax (apply 2to3 -f except)
fc0f829 CP-41819: Update print syntax: Apply 2to3 -f print (Part 1)
03f9ec7 CP-41819: Update print syntax: Apply 2to3 -f print (Part 2: stderr)
c2954e2 CP-41819: Convert print(..., file=sys.stderr) before exit()s to logging.fatal()
3827179 CP-41819: Convert debugging print(...)s to debug(...)

I tested the uses of logging to work as expected and pylint (in GitHub CI) ensured that I fixed any logging argument errors (logging functions need format strings) that I had initially made.

The combined change is small, and can easily reviewed at once (or commit by commit).