Allow User Registration Update using the applicationId from the URL segment

[robotdan]

Allow User Registration Update using the applicationId from the URL segment

Description

I want to be able to PUT or PATCH the User Registration using a URL that looks like this /api/user/registration/{userId}/{applicationId}.

Currently the applicationId is only accepted in the request body for this action.

If it is provided on the URL, it will take precedence over the request body. This allows a PATCH request such as

/api/user/registration/a7e04d53-0426-47e7-9cb6-bc3406d29c78/fd7faeb7-6d4b-4217-af1d-edef30902adf

{
  "registration": {
    "username": "Changed"
   }
} 

Previously it would have only worked as:

/api/user/registration/a7e04d53-0426-47e7-9cb6-bc3406d29c78

{
  "registration": {
    "applicationId": "fd7faeb7-6d4b-4217-af1d-edef30902adf"
    "username": "Changed"
   }
} 

The old way will still work. Need to update doc with this new option.