TODO

• Add support for custom ProtoBuf options in interceptors and server-side RPCs (closes Support options for Services and RPC #8)
• Add Java support through class-bridges (with multimode, closes Add Java-compatible API and generation structures #10)
• Add support for other request types such as metadata push and fire-and-forget through annotation type (closes Add support of metadata push and fire-and-forget request types in rRPC #9)
• Add support for ProtoBuf builtin types (they're already supported by generating regular classes, but I think we need some kind of bridge with types from like kotlinx.datetime, closes Add support for builtin protobuf types #11)
• Server Metadata Service (closes Create metadata service with information about Services, Methods and so on. #6)