Save metrics to JSON file for the extract tool

[nsyzrantsev]

Motivation

Sometimes it's necessary to review certain metrics after executing the barkit extract tool.

It might be a good idea to save these metrics to a JSON file:

1. The number of raw reads in both FASTQ files.
2. The number of reads after barcode extraction.
3. The number of found UMI, Sample, and Cell barcodes.

Realization

Introduce a new flag --json that specifies the path to the JSON file where the list of metrics will be saved.

{
  "reads_before": 5000000,
  "reads_after": 4999500
  "umi_count": 4999500,
  "cell_count": 0,
  "sample_count": 0
}