Allow running docker on windows for csvw-check behave tests

[NickPapONS]

Following some attempts to get csvw-check working in our windows behaviour tests in issue #851, it has become apparent that csvw-check does not work as expected when running on windows directly (i.e. installed through powershell and run by a command). We are not getting the expected results when validating CSVWs in terms of both the exit code (intentionally inputting invalid CSVWs gave exit code 0) and also are unable to capture the logs of the validation result (this means we can't make assertions on validation results, e.g. checking for specific errors).

Our proposed solution for this is to run csvw-check on windows the same way it is being done in our linux tests, through the use of docker. This will require the function _run_csvwcheck() in devtools to be altered so the else section no longer runs a command in the directory.

If implementing docker in windows goes smoothly (adding/installing it in windows-testing-setup.ps1) then the devtools code can simply remove the else part of the function, as both linux and windows environments can hopefully use the same DockerClient object to run csvw-check on the input metadata file. If this does not go as expected, you may need to do some further investigation on how to make docker available for use in the windows environment.