Add -Force to Expand-Archive

As noted in the console spew of this test:  https://helix.dot.net/api/2019-06-17/jobs/82bbddae-4a56-4002-b3ee-a8768311a92b/workitems/Microsoft.AspNetCore.SpaServices.Extensions.Tests-netcoreapp3.0/console it's quite possible for Node to be unpacked, but not on the path (generally on a helix machine it's because your parent process was created before the previous guy who unzipped Node and put it on the path ran, so only after reboot would you see the effect you want.