WIP: Provide detailed information about skyfiles

MERGE REQUEST

Overview

The goal is to make it possible for a client to get detailed information about skyfiles in the same way that's currently possible for siafiles via the /renter/files and /renter/file/*siapath endpoints.

The initial approach was to add a --root parameter to renterFileHandlerGET but that doesn't work well because it requires a specific siapath as parameter and changing that will change the method's usage too much.

A better approach is to change renterFilesHandler to support a --root parameter which would make it return information on all files under /fs instead of all files under /fs/home/user.

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