Add Invoke-VaasWorkflow

[gdbarron]

• Add Invoke-VaasWorkflow to trigger either a Test, Provision, or Discover machine/machine identity workflow. This is super helpful when looking to automate renewal and provisioning of certificates that may expire soon. For example to renew and provision certs expiring within 30 days:

  Find-VaasObject -Type MachineIdentity -Filter @('and', @('certificateValidityEnd', 'lt', (get-date).AddDays(30)), @('certificateValidityEnd', 'gt', (get-date))) | ForEach-Object {
      $renewResult = $_ | Invoke-VenafiCertificateAction -Renew
      $_ | Invoke-VaasWorkflow -WorkflowName 'Provision'
  }