Move from UIShelf to TopbarPlus v3

[ryanlua]

Description

Migrates from UIShelf to TopbarPlus v3 since UIShelf is discontinued.

Related Issues

Closes #57

Changes Made

• Add TopbarPlus to Wally
• Remove UIShelf from Wally
• Update Satchel with support for TopbarPlus

Checklist

• [ ] I have tested these changes thoroughly.
• [x] I have reviewed my code for any potential errors or issues.
• [x] I have followed the code style guidelines for this project.

Additional Notes

Code of Conduct

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