* [PM-3176] Extract IOrganizationService.SaveUserAsync to a command
* [PM-3176] Enabled nullable on command
* [PM-3176] Removed check that was not working
* Add new endpoint for creating client organizations in consolidated billing
* Create empty org and then assign seats for code re-use
* Fixes made from debugging client side
* few more small fixes
* Vincent's feedback
* Fix assigning Manage access to default collection
The previous implementation did not work when creating an org as a
provider because the ownerId is null in OrganizationService.SignUp.
Added a null check and handled assigning access in ProviderService
instead.
* Tweaks
