Add RTTM capability to exports sub-module

[damian-romero]

Description

• DOVER-lap is a system for turn diarisation IRR and for combining two or more annotator's diarization hypotheses
• DOVER-lap uses the RTTM file type
• We want to add RTTM file type support to the exports sub-module
• We need to be able to create joint and separate files for DOVER-lap testing for A) Overlapping turns, B) Non-overlapping turns, and C) both. See this issue for why.

Implementation

Implement in json_parser.py as:

    parser.add_argument("-rttm", "--diarisation-rttm", action="store_true",
                        help='Creates Rich Transcription Time Marked (RTTM) files from LabelStudio exports\
                           inside ../output/.')

This would create three files for each interview:

• [interview-id]_overlapping.rttm
• [interview-id]_non_overlapping.rttm
• [interview-id]_combined.rttm

Steps

• Add turn length information Find overlapping turns #11
• Add turn overlapping information Find overlapping turns #11
• Add rttm file support Add support for rttm outputs in exports sub-module #12
• Manlually check overlapped turns in turn_diarisation.csv against LabelStudio
• Check well-formedness of RTTM files using: https://github.com/nryant/dscore#rttm