Investigate cross-compatibility between windows / mac devices when using the playbook locally

[aircwo]

When working with the playbook code on a windows device, some aspects of the development process simply don't work due to the use of Mac only features. More issues could be present but are unknown due to the lack of testing on a windows machine.

Most notably:
The build command npm run build wont run as env is a mac specific command. For this, a package such as env-cmd may work as a replacement.

Additionally:
When running a windows machine the url will default to:
http://localhost:8080/'nhsbsa-digital-playbook'/
when it should be:
http://localhost:8080/nhsbsa-digital-playbook/
This is due to the start command passing a string prefix which is dealt with differently on different operating systems.

The reason for this discussion instead of an issue, is the fact that I think the issues need exploration and confirmation by a windows user to determine the next steps for what should be fixed.