Introduce the Bluetooth transport layer

**Description**
Add support for a new Bluetooth transport layer to enable communication with remote boards/devices over Bluetooth.

**Motivation**
The current transport system does not support Bluetooth. Adding a Bluetooth layer will enable remote control and communication with Bluetooth-enabled devices, which is currently impossible with the existing setup.

**Requirements**
- Support for Arduino boards using the HC-05 Bluetooth module.
- Support for ESP32 boards with built-in Bluetooth capability.

**Notes**
Bluetooth acts as a virtual serial port. The implementation may consist of aliasing or reusing existing serial port abstractions with minimal changes.

**API Changes**
None. This feature adds an additional transport layer but does not modify existing APIs.