Add option to enable prelude serialization

[srchase]

This PR adds an option to enable serializing prelude shapes.

By default, prelude shapes are filtered from the output of SmithyIdlModelSerializer.serialize().

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mtdowling]

What's the motivation of this change?

[srchase]

What's the motivation of this change?

SmithyIdlModelSerializer will be used by the Hover capability of the Language Server to show the information about shapes/traits in a model. I want to make this available for showing the same information about prelude shapes.

For example, if @input is hovered on in a client, the following will be shown:

/// Specializes a structure for use only as the input of a single operation.
@trait(
    selector: "structure",
    conflicts: [output, error],
    breakingChanges: [{change: "presence"}]
)
structure input {}