🔨 add droplet utils

[migbro]

Description

To accommodate a minor refactor in the scRNA QC output, adding this package. It will allow for writing of QC-filtered 10X count matrices in h5 format

Fixes # https://d3b.atlassian.net/browse/BIXU-1048

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Tested locally on input https://cavatica.sbgenomics.com/u/d3b-bixu/kf-dev-single-cell-rna/files/666b526627374715fc3e1716/ with a revised QC script
• Successfully wrote h5 formatted output an read it back in to seurat without error
  Test Configuration:

• Environment:
• Test files:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings
• I have committed any related changes to the PR