Suggestion: Add USART Handler Abstraction for More Flexible Integration

[Robinsssson]

Currently, the STM32 ATC library assumes that USART transmission and initialization are implemented using the HAL library. While this approach works well for users relying on HAL, it creates compatibility issues for those using alternative libraries such as the Standard Peripheral Library (Std library).

To address this, I suggest introducing a USART handler abstraction, similar to how the cJSON library allows users to customize malloc and free functions. This would make it possible for developers to define their own USART send, receive, and initialization functions without being tied to HAL.

[nimaltd]

hi, ok. i will see