Increase HTTP Request Timeout

[peombwa]

We should:

• Increase the timeout value to something > 100 seconds since retried requests can fail if the cumulative time exceeds a client's default of 100 seconds. e.g., retry-after of 40 seconds with a retry-attempt of 3 = 120 seconds.
• Provide an option for customers to set their preferred HTTPClient.Timeout value. This can be in the form of:
  • Global variable $global:MgClientTimeout.
  • Parameter on Connect-MgGraph -ClientTimeout.
  • A new command - Set-MgContext.