Agora RTC Objective-C API Reference Refactor

### - f -

- featureName : AgoraLiveStreamAdvancedFeature
- filePath : AgoraAudioRecordingConfiguration , AgoraLogConfig
- fileRecordOption : AgoraAudioRecordingConfiguration
- fileSize : AgoraMediaPlayerCacheStatistics , AgoraMediaRecorderInfo
- fileSizeInKB : AgoraLogConfig
- firstAudioPacketDuration : AgoraChannelStats
- firstVideoKeyFramePacketDuration : AgoraChannelStats
- firstVideoPacketDuration : AgoraChannelStats
- followEncodeDimensionRatio : AgoraCameraCapturerConfiguration
- format : AgoraVideoFrame
- forward : AgoraMetachatPositionInfo , AgoraRemoteVoicePositionInfo , AgoraSpatialAudioZone
- forwardLength : AgoraSpatialAudioZone
- fps : AgoraDirectCdnStreamingStats , AgoraImageTrackOptions
- frameLossRate : AgoraRtcRemoteVideoStats
- frameRate : AgoraCameraCapturerConfiguration , AgoraScreenCaptureParameters , AgoraScreenVideoParameters
- framerate : AgoraSimulcastStreamConfig
- framesPerSecond : AgoraEncodedVideoFrameInfo
- frameType : AgoraEncodedVideoFrameInfo
- frozenRate : AgoraRtcRemoteAudioStats , AgoraRtcRemoteVideoStats
- frozenRateByCustomPlcCount : AgoraRtcRemoteAudioStats
- frozenRatioPercent : AgoraWlAccStats