Support Windows for package testing

[taldcroft]

Description

This makes the testr + ska_testr pair work on Windows. Key changes:

• Use subprocess.run for testing on Windows, but still use pexpect on linux / Mac to support bash test scripts (and for consistency with historical behavior).
• Drop support for overwriting an existing test output directory. I don't think this was being used. This change was needed to get rid of a call to rsync.
• Drop support for a get_version_id bash script that makes the test directory name. Instead just hardwire something reasonable into testr.
  • Note that a path name that includes colons breaks both Windows and the Ska.engarchive regression test, so colon is changed to dash.
• PEP8 fixes.

Testing

• [N/A] Passes unit tests on MacOS, linux, Windows.
• Functional testing

Functional testing

Windows

The following runs to completion and gives the expected results. There are some fails that have the correct diagnostic information and passes that look good.

python -m testr.packages --root C:\Users\aldcroft\git/ska_testr --test-spec=test_spec_SKA3

I did not verify the output of the XML test results. Most likely things are OK, but this will be done as part of getting automated Windows CI running.

Linux (HEAD)

The following runs to completion and gives the expected results.

python -m testr.packages --root ~/git/ska_testr --include=agasc --include=Ska.engarchive --include=acisfp_check

Fixes #31

[taldcroft]

after removing the get_version_id scripts, where are logs placed now?

The only thing different is using testr.packages.get_version_id() instead of running a bash script ska_testr/get_version_id. So should be an easy change, and arguably a better implementation.