Fix validateWorkersVersions.ps1 script

[aishwaryabh]

Issue describing the changes in this PR

With the refactor of the host, each Worker.props file has been split into eng/build/Worker.[WorkerName].props, rather than having the worker references directly in the csproj. The validateWorkersVersions.ps1 script has been updated to reflect this change.

Example of running validateWorkerVersions.ps1 -Update -HostVersion 4.1037.0:

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by Fixing in-proc pipeline #4250
• I have added all required tests (Unit tests, E2E tests)

[jviau]

Coming to realize how much manual ingestion of the host repo the core tools repo has. Would be good to see how we can decouple this in the future.

[Francisco-Gamino]

Thank you @aishwaryabh for updating this script. Could you please port this change to the in-proc branch? Thanks again.