[BUG] API Document generation does not parse request parameters for RPC types (Dubbo/SOFA/TARS/gRPC)

### Is there an existing issue for this? - [x] I have searched the existing issues ### Current Behavior The API document generation in `ApiDocRegistrarImpl.getDocument()` uses `OpenApiUtils.generateDocumentParameters()` for all RPC types without distinction. This method only supports parsing Spring Web annotations (`@RequestParam`, `@RequestPart`, path variables) for HTTP-style parameters. For non-HTTP RPC types (Dubbo, SOFA, TARS, gRPC), it fails to extract any meaningful request parameter information, since these RPC types do not use Spring Web annotations. As a result, the generated API document for RPC types contains `responseType` (response details) but has empty/missing request parameter details — the document only has response, no request. ### Expected Behavior _No response_ ### Steps To Reproduce _No response_ ### Environment ```markdown ShenYu version(s): ``` ### Debug logs _No response_ ### Anything else? _No response_