Windows build

[JustCallMeRay]

Describe the bug
The windows build is broken at the CMake configure step.
Seems to be path separators in the source dir argument, CMake prefers the Linux style paths.

To Reproduce
Steps to reproduce the behaviour:

1. Run the windows build
2. See the windows build fails in the configure CMake step

Expected behaviour
A clear and concise description of what you expected to happen.

• The windows build to run
• Tests to run

Desktop (please complete the following information):

• See github actions on master for full log and machine information

[JustCallMeRay]

The Windows build now runs from start to finish including running all the tests

A test does fail on Windows but I don't intend to fix it under this ticket (feels out of scope) though I can if asked, either as a new ticket or under this one.