Bubble code refactor

MERGE REQUEST

MR Guidelines

Overview

As a follow up for the bubble scheduler MR, this MR does some refactoring to pull more bubble specific code into the bubble subsystem. Updates include:

1. Moving the renter's BubbleMetadata method into the bubble subsystem
2. Moving managedPerformBubbleMetadata into the bubble subsystem and renaming to managedPerformBubbleUpdate
3. Refactor the call to bubble the parent directory into its own method with unit test.
4. Move the benchmark into the bubble subsystem and update results.
5. A few method prefix updates from managed to call
6. Updates to the renter README

Example for Visual Changes

Checklist

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

• All new methods or updated 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 workflow
• Issue added to Sia-UI repo for new supporting features
• Changelog File Created

Issues Closed

Part of #4514