title: Get User in Office 365 by ImmutableId
body: <ol>
  <li><p>I am looking to get the Office 365 User details based on his ImmutableId. However there is no direct attribute to supply the ImmutableId and hence only way currently is to supply it in where-object on the Get-MSOLUser. However this would loop through all users and hence is not a good solution. So is there any other way?</p></li>
  <li><p>I am trying to build a tool that will read the Users in On-Prem AD and do some licensing work on O365. There could be multiple AD's and hence I started looking at ImmutableId to uniquely identify a user. Is using 'ImmutableId' the correct approach?</p></li>
  </ol>