Agora RTC Objective-C API Reference Refactor

### - h -

- heartbeatInterval : AgoraRtmClientConfig
- height : AgoraEncodedVideoFrameInfo , AgoraExtVideoFrame , AgoraFacePositionInfo , AgoraMediaRecorderConfiguration , AgoraMetaSceneDisplayConfig , AgoraOutputVideoFrame , AgoraRtcRemoteVideoStats , AgoraVideoFilterFrame , AgoraVideoFrame , AgoraVideoLayout , AgoraVideoLayoutInfo , WatermarkBuffer
- highLightColor : AgoraScreenCaptureParameters
- highLighted : AgoraScreenCaptureParameters
- highLightWidth : AgoraScreenCaptureParameters
- hwDecodingLevel : AgoraVideoCodecCapLevels