Support default values for schema properties

The generator skips the default values for Components.Schemas. It would be nice to have a default value for the property itself and in the initializer. I made an example:

Spec example:

Current:

Desired:

Start at the generator entry point for Components.Schemas and compare the linked Spec example with the Current and Desired outputs. Trace how schema property values become generated declarations and initializers; done means schema defaults appear in both places as shown in the Desired example.

Written by the indexing model from the issue text.