Update the release process to sign Windows exe to limit signature usage

Presently, Digicert has limited. the number of signatures with the new certificate for windows.
So, we need to add a flag to enable the "sign the exe", when set to true manually.
By default the flag is set to false.
Also to avoid the unnecessary sign of executabes, we need to add separate pipeline step/job to do the signing  job; so we can skip it when needed