Reimplement solution as a cross-browser extension

[andrealexandre]

This extension should be cross-browser and workable for any jira based endpoint.

Documentation:
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions

Goals:

• Figure how to detect Jira issue view
• Add view for uploading file directly
• pick replacement for csv parser lib
• Port logic from C# into JS
• Hand craft CSV file for testing
• Test with previous CSV file
• Look into unit tests for code (if possible)
• Look for real work use case of csv files
• Open PR and ask for reviewing

[andrealexandre]

Good starting point: https://github.com/EmailThis/extension-boilerplate