Update Python base version from 3.6 to 3.8. For Zed the minimum
Python runtime versions are Python 3.8 and 3.9 [1]. As a third
Python version I also added 3.10 already.
Removed ThreadedHTTPServer and replaced it with ThreadingHTTPServer from
standard library, which is new in Python 3.7.
[1]: https://governance.openstack.org/tc/reference/runtimes/zed.html
Change-Id: I035c569b4feaa23b00c0cad50c36aaecf06f7848
There were a few unit test files that didn't match their
code counterparts, so were a little hard to find. Moved
things around to line-up better, leaving only a handful
of exceptions to ignore. Added a test script to check
things so it won't happen again, copied from Neutron.
No actual code was changed, files were just moved around.
Change-Id: I6d84047b3481a2bf6bf9bd17d482fb504dbc752b