global-config/realms endpoint does not separately handle "realm aliases" and "DNS aliases"

Bug description

The REST endpoint 'global-config/realms' does not distinguish between 'realm aliases' and 'DNS aliases', so it's impossible to intentionally set one or the other.

 How to reproduce the issue

Details steps outlining how to recreate the issue (remove this text)

1. Configure AM
2. Use API explorer to retrieve realm config for root realm (
   curl -X GET --header 'Accept: application/json' 'http://am6004.test.xyz:8080/am/json/global-config/realms/Lw')
3. Use API explorer to set 'realm alias', not 'DNS alias'.

Expected behaviour

There should be a separate JSON property for the realm alias

Current behaviour

No distinction between realm alias and DNS alias possible

JSON payload is always

{
  "aliases": [
    "am6004.test.xyz",
    "am600.test.xyz",
    "openam",
    "am6004"
  ]
}

Which value are realm aliases and which one are DNS aliases?