Async IDC: rust receiver bindings - #6375

Description of Changes

Taken receiver side out from: #6001.

Adds Rust receiver bindings for intermodule reducer calls.

It can be reviewed through commits:

• Do callback validation
• Generate Rust receiver types, reducer metadata, and parameter-checking helpers, reusing client codegen where possible.
• Wire receiver-binding generation into the CLI.
• Namespace registered receiver types by dependency name to avoid collisions.
• Add CLI smoke tests that generate bindings for two dependencies and compile a sender using both.

API and ABI breaking changes

NA

Rollback safety impact

N/A.

Expected complexity level and risk

Testing

• Added tests.