Support Paraformer online recognizer

- Updated `.gitignore` to include new Paraformer models. - Added `serde` and `serde_json` dependencies in `Cargo.toml` and `Cargo.lock`. - Introduced `OnlineRecognizerJsonResult` and `OnlineRecognizerResult` structs for handling recognition results. - Implemented `ParaformerOnlineRecognizer` with configuration options and transcription capabilities. - Added a new example for streaming transcription using Paraformer.