[ruby|client] Fix unmarshalling errors of enums inside other objects

[isimluk]

Ruby|Client autogenerated model classes for Enums do not expose openapi_one_of method. Instead they expose openapi_any_of method like:

  # List of class defined in anyOf (OpenAPI v3)
  def openapi_any_of
    [
      :String
    ]
  end

Both types (objects and enums) do respond to build() method.

Addressing:

models/redacted_model.rb:1750:in `_deserialize': undefined method `build_from_hash' for XyzModel:Module (NoMethodError)

        klass.respond_to?(:openapi_one_of) ? klass.build(value) : klass.build_from_hash(value)
                                                                       ^^^^^^^^^^^^^^^^
        from models/redacted.rb:1705:in `block in build_from_hash'

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• PR checklist

[isimluk]

/cc ruby technical committee heroes: @cliffano, @zlx, @autopp

[wing328]

lgtm. thanks for the PR.