Support advanced UART customization (#4465)

* Add methods to get hardware uart details.

* Fix `setRxBufferSize` error.

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Co-authored-by: Your Name <you@example.com>

esphome/components/uart/uart_component_rp2040.h

@@ -30,6 +30,9 @@ class RP2040UartComponent : public UARTComponent, public Component {
 
   uint16_t get_config();
 
+  bool is_hw_serial() { return this->hw_serial_; }
+  HardwareSerial *get_hw_serial() { return this->serial_; }
+
  protected:
   void check_logger_conflict() override {}
   bool hw_serial_{false};