feat(layout): extend layout functionality

[NickTheWilder]

Starts the first part of #535 to hide specific rectangles based on the user's configuration file. Inspired from the review comments in #545

Opened as a draft bc I've limited out on knowledge of the application (and rust).

TODO:

• [ ] Set the focused state to the first 'found' rectangle.
• [x] Update default configuration file.
• [x] Extend README.

Feel free to takeover and create a new branch or directly add commits here.