Fix and add functions in speaker utils
# What does this PR do ?

This PR fixes bugs for certain cases and adds few functions. Previously, write_rttm2manifest function had following issues:

(1) Offset is not considered
(2) Occasionally, the function was returning the segments outside the given (offset, offset+duration) range.

The newly written part is compared with the original code, and confirmed to 

**Collection**: [Note which collection this PR will affect]

ASR

# Changelog 
- Add specific line by line info of high level changes in this PR.

Added following functions in speaker_utils.py.
These functions are needed to extract oracle VAD stamp from manfiest file, considering the offset and duration.
In addition, these functions are designed for the future use for streaming diarization. 

get_uniq_id_with_dur()
getSubRangeList()
getMinMaxOfRangeList()
getMergedRanges()
int2fl()
fl2int()
combine_int_overlaps()
combine_float_overlaps()
getOverlapRange()
isOverlap()

and modified following functions:
write_rttm2manifest() - to resolve existing issues
segments_manifest_to_subsegments_manifest() - Now, if include_uniq_id = True, the function adds uniq_id to the created subsegment manifest file. This is for using segmentation files for truncated (chopped) diarization dataset, where uniq_id is overlapped if not specified. (One audio file creates multiple 30~40sec utterances and these short utterances should be identifed too.)

Details can be found in the docstring in each function definition.

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**PR Type**:
- [x] New Feature
- [x] Bugfix
- [ ] Documentation

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# Additional Information
* Related to # (issue)
