Fix window path escape on java override

What does this MR do and why?

Currently if using windows slashes in your startup command and you use java override all \ slashes will be escaped due to shlex library. This MR marks windows vs unix as such and marks posix as true or false accordingly.

Resolves #187 (closed)

How to set up and validate locally

Using windows with \ slashes and an @ symbol at the beginning of the path in your startup command and use the java override feature.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• Have you checked this doesn't interfere/conflict/duplicate someone elses work?
• Have you fully tested your changes?
• Have you resolved any lint issues?
• Have you assigned a reviewer?
• Have you applied correct labels?