The current Rust workspace isn't as consistent as it could be. To make
navigation a bit easier, we move a few crates around. Generally, we
follow the idea that entry-points should be at the top-level. `rust/`
now looks like this (directories only):
```
.
├── cli # Firezone CLI
├── client-ffi # Entry point for Apple & Android
├── gateway # Gateway
├── gui-client # GUI client
├── headless-client # Headless client
├── libs # Library crates
├── relay # Relay
├── target # Compile artifacts
├── tests # Crates for testing
└── tools # Local tools
```
To further enforce this structure, we also drop the `firezone-` prefix
from all crates that are not top-level binary crates.
In order to experiment with alternative GUI libraries, we extracted a
`gui-client-common` crate that would hold GUI-library agnostic code.
We've since upgraded to Tauri v2 and settled on that as the GUI
framework for the Windows and Linux Firezone Clients. Therefore this
abstraction is unnecessary and can be removed again.
This makes it easier to work on the GUI client and also allows the
compiler to flag unused code more easily.
