Impement directory upload support for Skynet

MERGE REQUEST

Overview

Implement support for uploading entire directories. At this stage each file will be uploaded individually and will have its own skylink.
The implementation should leave room for the future implementation of a --pack flag that will lead to a single skylink being generated for the entire uploaded directory.

Example for Visual changes (ie Screenshot)

Issues Closed

Part of #3871 (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