feat(uart): backports UART pin attachment from 3.0.0 to 2.0.15 (espressif#9176)

* feat(uart): backports UART pin attachment from 3.0.0 to 2.0.15

* Fix (uart): Fixes additional Serial HardwareSerial errors for 2.0.14

* Update esp32-hal-uart.c

* Update HardwareSerial.h

* Apply suggestions from code review

* Fixes UartAvailableForWrite espressif#9319

* Fixes  (set RX/TX buffer size)

Author: SuGlider