add file packaging

MERGE REQUEST

Overview

File packing:

The goal is to pack a list of files into sectors as efficiently as possible (little unused space between files). To complicate matters, there are alignment requirements on the files. See comments in packing.go for more information.

Example for Visual changes (ie Screenshot)

Issues Closed

Checklist

Review and complete the checklist to ensure that the MR is complete before assigned to an approver.

• All new methods, or updating methods have clear docstrings
• Testing added or updated for new methods
• Any new packages are added to Makefile and .gitlab-ci.yml
• API documentation updated for API updates
• Module README.md updated for changes to work flow
• Issue added to Sia-UI repo for new supporting features
• Changelog updated