Export email address of an employee's manager for all employees

 I'd like to get a report in csv for all employees showing the email address of their Primary Manager.
Such a report that contains an employees email and their managers will be useful to build automation to keep Azure AD uptodate with manager relationships.

eg in powershell

$ManagerObj =Get-AzureADUser -ObjectId $man_email
Set-AzureADUserManager -ObjectId $emp_email -RefObjectId $ManagerObj.ObjectId

Alternatively a SCIM interface would do the trick - allowing updates to be pushed into AzureAD.