Agora RTC Objective-C API Reference Refactor

Here is a list of all functions, variables, defines, enums, and typedefs with links to the files they belong to:

### - g -

- getAgoraCertificateVerifyResult() : AgoraBase.h
- getAgoraCurrentMonotonicTimeInMs() : AgoraBase.h
- getAgoraExtensionControl() : AgoraExtensionProviderEntry.h
- getAgoraLicenseCallback() : AgoraBase.h
- getAgoraRtcEngineErrorDescription : IAgoraRtcEngine.h
- getAgoraRtcEngineVersion : IAgoraRtcEngine.h
- getAgoraSdkErrorDescription() : AgoraBase.h
- getAgoraSdkVersion() : AgoraBase.h