Direct access to structure fields

[kubukoz]

It would be "cool" (and probably useful in a bunch of ways) to have access to a particular Field instance, knowing the member name.

For example:

structure Hello {
  @required foo: String = "woop"
}

println(Hello.fields.foo.getDefaultValue: Option[String])

This would sort of mirror how you can already access the individual alts of a generated union shape.

[meldmy]

We need this feature in our project to avoid duplicating default values in the code base having a smithy with default values