Add execution_time to Windows

[HeyItsGilbert]

Describe the Enhancement:

After a shell out on Windows, the execution_time property is not available.

Describe the Need:

Being able to track execution time could be desirable when troubleshooting issues.

Current Alternative

Track time in the process maybe? Would be very ugly.

Can We Help You Implement This?:

I have a PR coming.

[dafyddcrosby]

@tpowell-progress this issue can be closed (was fixed with #247)