Add Tests for Rust Code and Generated Bindings

[tareknaser]

We need to add tests for the:

• Rust code
• Generated bindings code

Include unit tests for both, and end-to-end (E2E) tests for the Tauri app (sending and receiving). These should also be run in our CI.

Related discussions:

• Iroh Integration Prototype #1 (comment)
• Iroh Integration Prototype #1 (comment)