Agora RTC Objective-C API Reference Refactor

### - f -

- faceCaptureAppId : AgoraMetaSceneConfig
- faceCaptureCertificate : AgoraMetaSceneConfig
- failedUsers : AgoraRtmTopicSubscriptionResponse
- featureName : AgoraLiveStreamAdvancedFeature
- features : AgoraRtmJoinChannelOption , AgoraRtmSubscribeOptions
- filePath : AgoraAudioRecordingConfiguration , AgoraLogConfig , AgoraRtmLogConfig , AgoraSnapshotConfig
- fileRecordOption : AgoraAudioRecordingConfiguration
- fileSize : AgoraMediaPlayerCacheStatistics , AgoraMediaRecorderInfo
- fileSizeInKB : AgoraLogConfig , AgoraRtmLogConfig
- firstAudioPacketDuration : AgoraChannelStats
- firstVideoKeyFramePacketDuration : AgoraChannelStats
- firstVideoPacketDuration : AgoraChannelStats
- focalLengthType : AgoraFocalLengthInfo
- followEncodeDimensionRatio : AgoraCameraCapturerConfiguration
- format : AgoraVideoFrame
- forward : AgoraMetaPositionInfo , AgoraRemoteVoicePositionInfo , AgoraSpatialAudioZone
- forwardLength : AgoraSpatialAudioZone
- fps : AgoraDirectCdnStreamingStats , AgoraImageTrackOptions , AgoraMediaRecorderConfiguration
- frameLossRate : AgoraRtcRemoteVideoStats
- frameRate : AgoraCameraCapturerConfiguration , AgoraScreenCaptureParameters , AgoraScreenVideoParameters
- framerate : AgoraSimulcastStreamConfig , AgoraStreamLayerConfig
- framesPerSecond : AgoraEncodedVideoFrameInfo
- frameType : AgoraEncodedVideoFrameInfo
- frozenRate : AgoraRtcRemoteAudioStats , AgoraRtcRemoteVideoStats
- frozenRateByCustomPlcCount : AgoraRtcRemoteAudioStats
- frozenRatioPercent : AgoraWlAccStats