refactor(analyzer.core): refactor AnalyzerResult

- Put frame_metadata and label_metadata inside data_object
- No more subclasses for analyzerResult
- Put subclasses in data_object (subclasses of DataObject: one per (data_mode, time_mode) combination
- Add 'y_value' and 'y_unit' key for data_object (to deal with 2D array where the y-value is a data and may have a unit like spectrogram (y_value = frequnecies, y_unit=Hz))