Add support for derived types to the default TypeRegistry

[APErebus]

Background

If you supply a complex base type as part of the request message, the TypeRegistry doesn't know how to resolve any derived types.

This PR updates the TypeRegistry to check the assembly the base type is in as well as any extra assemblies provided during setup for any derived types.

Results

I chose to implement a new TypeRegistryBuilder to allow consumers to configure the built-in type registry without having to create their own (similar to how we can configure the Message Serializer as part of the HalibutRuntimeBuilder.

We also only look for ExportedTypes() in the assemblies, so types that are private/protected/internal are not registered.

I've added some unit tests to cover the new serialization behaviour.

Shortcut story: [sc-62805]

How to review this PR

Quality :heavy_check_mark:

Pre-requisites

• [ ] I have read How we use GitHub Issues for help deciding when and where it's appropriate to make an issue.
• [ ] I have considered informing or consulting the right people, according to the ownership map.
• [x] I have considered appropriate testing for my change.

[shortcut-integration[bot]]

This pull request has been linked to Shortcut Story #62805: Update Halibut to support derived types in request messages.