Ability to disable default enum value in client

[eduanb]

Is your feature request related to a problem? Please describe. When creating clients with a well-defined enum that will never expand, like the direction of ASC and DESC, it doesn't make sense to be forced to handle the __UNKNOWN_VALUE with when statements.

Describe the solution you'd like A global setting is enough for my use case. However, I can see it being useful to have per enum config.

    graphql {
        client {
            generateEnumDefaultValue = false
        }
    }