Agora RTC Objective-C API Reference Refactor

### - i -

- INJECT_STREAM_STATUS_BROKEN : agora::rtc
- INJECT_STREAM_STATUS_START_ALREADY_EXISTS : agora::rtc
- INJECT_STREAM_STATUS_START_FAILED : agora::rtc
- INJECT_STREAM_STATUS_START_SUCCESS : agora::rtc
- INJECT_STREAM_STATUS_START_TIMEDOUT : agora::rtc
- INJECT_STREAM_STATUS_START_UNAUTHORIZED : agora::rtc
- INJECT_STREAM_STATUS_STOP_FAILED : agora::rtc
- INJECT_STREAM_STATUS_STOP_NOT_FOUND : agora::rtc
- INJECT_STREAM_STATUS_STOP_SUCCESS : agora::rtc
- INJECT_STREAM_STATUS_STOP_TIMEDOUT : agora::rtc
- INJECT_STREAM_STATUS_STOP_UNAUTHORIZED : agora::rtc