Paths with spaces are an issue on Windows and our current powershell
scripts are not sufficiently hardended against their use.
This PR removes promlematic commandlets that do not work well with paths
with spaces and adds escape quotes in other areas where this could be an
issue.
Unit tests on Windows are supposed to pass for any PR to pass CI.
However, the return code for the unit test command was not being
checked, which meant this check was always passing (effectively
disabled). This PR
* Properly checks the result of the unit tests and fails if the
unit tests fail
* Fixes (or disables on Windows) a number of tests which have
"drifted" out of support on Windows since this check was
effectively disabled
