Client Generator should respect defaults

[paulpdaniels]

In the server case we obviously have limitations around being able to create type safe default values, however for the client we should be able to respect the default values (at the very least for primitives). Consider the following generated code:

input FindEmailStatusInput {
  userId: String!
  personId: ID!
  companyId: ID
  isExternalCompanyId: Boolean! = false
}

final case class FindEmailStatusInput(
  userId: String,
  personId: String,
  companyId: scala.Option[String] = None,
  isExternalCompanyId: Boolean
)

Here it should be relatively trivial to support the default parameter. For non-primitives we could ignore the, add a configuration that allows specifying how to transform them (somewhat brittle), or we could attempt to recurse through the type description and line up the fields with their declarations.