add attribute converters for "standard" values

ianbotsf commented 3 months ago

Issue \

Related to #472

Description of changes

This change fills out new ValueConverter implementations for "standard" types (using a somewhat arbitrary definition of the word "standard"). Specifically they include:

Various scalar types such as String, Int, Boolean, etc.
Collections like List, Map, and Set
smithy-kotlin runtime types like Url, Document, and Instant
Nullable types

I also introduced a ValueConvertersTest class to streamline unit testing with a DSL. I'll be interested to hear feedback on whether this is effective or if it just obscures things.

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