feat: official cardwire gui

[luytan]

Description

Making Cardwire more beginner-friendly is one of my priorities for the next release, this is why i'm introducing a new crate to the project, cardwire-gui.
The goal is to give the user an alternative to cardwire-cli, thus making the CLI optional for users who do not want to use a terminal

The GUI will be made using the iced library.

The primary focus will be to port the CLI functionalities to the GUI, then, in a second PR, to style the GUI.

TO-DO

• List GPUs
• Manage the mode
• Switch between pages
• Manage cardwired's settings
• Manual GPU management (blocking, lsof)
• About Page
• PCI-Devices list with an export button (copied into the wayland-clipboard)
• Debug page with a warning
• Real-time updating GPU powerstate

Checklist:

• My code follows the style guidelines of this project (cargo fmt)
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the mdBook documentation
• My changes generate no new warnings (clippy/clang)
• New and existing unit tests pass locally with my changes (either use nix flake check or wait for the ci)