Show errors in the UI

[JadKHaddad]

This involves a global or local error handler. All backend functions are called in appState. So we can handle the erros there (globally) are propagate them to the caller (locally).

We also need a background errors channel. Just like the serial_packet_event and serial_ports_event in App.vue: error_event. therefore we will:

• Define error model, Rust & Typescript
• impl the channel in rust
• impl the channel in vue

[JadKHaddad]

56 was merged