Add support for blocking server stubs

### Is your feature request related to a problem?
Currently there's a blocking client v2 stub generated, but we don't have a server stub to match.

### Describe the solution you'd like
A simplified api surface for developers who run on virtual threads for example, with a blocking-native api.

### Describe alternatives you've considered
The closest thing to programming with a blocking api is the kotlin coroutines generated stubs.

### Additional context
From what I can tell there's existing code in the repo to support blocking server stubs, but code generation does not exist for it.

Start by tracing the existing generated blocking client v2 stub and the repository's existing blocking server-stub support, then find the code-generation entry points that connect them. Confirm the generated blocking-native server API and validate it against the existing server behavior and generation tests; done means developers can generate a matching blocking server stub for virtual-thread use.

Written by the indexing model from the issue text.