Agora RTC Objective-C API Reference Refactor

### - e -

- e2e_delay_ms : RemoteAudioTrackStats
- e2eDelay : RemoteVideoStats , RemoteVideoTrackStats
- e2eDelayPercent : WlAccStats
- echo_return_loss : ILocalUser::AudioProcessingStats
- echo_return_loss_enhancement : ILocalUser::AudioProcessingStats
- effect_type : ILocalAudioTrack::LocalAudioTrackStats
- eglContext : ExternalVideoFrame
- EglContextType : TextureInfo
- eglType : ExternalVideoFrame
- elapsedTime : VideoRenderingTracingInfo
- elapsedTimeMs : AudioPcmDataInfo
- empty_ : OptionalStorageBase< T >
- enableAlphaMask : VideoCanvas
- enableAudio : EchoTestConfiguration
- enableAudioDevice : AgoraServiceConfiguration
- enableAudioProcessor : AgoraServiceConfiguration
- enableAudioRecordingOrPlayout : ChannelMediaOptions , RtcConnectionConfiguration
- enableBuiltInMediaEncryption : ChannelMediaOptions
- enableCache : MediaSource
- enabled : ILocalAudioTrack::LocalAudioTrackStats
- enableHighLight : ScreenCaptureParameters
- enableLocalPlayback : AudioTrackConfig
- enableMultiAudioTrack : MediaSource
- enableVideo : AgoraServiceConfiguration , EchoTestConfiguration
- enableWriteFlvFile : RtmpConnectionConfiguration
- encode : AudioRecordingConfiguration
- encode_frame_rate : LocalVideoTrackStats
- encodedBitrate : LocalVideoStats
- encodedFrameCount : LocalVideoStats
- encodedFrameHeight : LocalVideoStats
- encodedFrameOnly : VideoSubscriptionOptions , VideoTrackInfo
- encodedFrameWidth : LocalVideoStats
- encoder_type : LocalVideoTrackStats
- encoderBitrateControlMode : RtmpStreamingVideoConfiguration
- encoderHwSwMode : RtmpStreamingVideoConfiguration
- encoderOutputFrameRate : LocalVideoStats
- encodingPreference : AdvanceOptions
- encodingType : AudioEncodedFrameObserverConfig
- encryptionKdfSalt : EncryptionConfig
- encryptionKey : EncryptionConfig
- encryptionMode : EncryptionConfig
- eventHandler : RtcEngineContext
- excludeWindowCount : ScreenCaptureParameters
- excludeWindowList : ScreenCaptureParameters
- expanded_noise_samples : RemoteAudioTrackStats
- expanded_speech_samples : RemoteAudioTrackStats
- expected_bitrate_bps : DownlinkNetworkInfo::PeerDownlinkInfo
- expectedDownlinkBitrate : LastmileProbeConfig
- expectedUplinkBitrate : LastmileProbeConfig
- ext_seqnum : ILocalUser::LocalAudioDetailedStats
- extension_name : IExtensionProvider::ExtensionMetaInfo
- extraInfo : ContentInspectConfig , PublisherConfiguration