[HWCDC] Improve HW CDC Implementation (#5643)

This pull request contains a few fixes and improvements to the HWCDC implementation.
- Rework `HWCDC::write()` to accept unlimited data
- Add Semaphore to guard the TX Ring Buffer
- Add events support
- Remove unnecessary 1200bps touch for flashing over HWCDC
- Fix `HardwareSerial::setDebugOutput()` not resetting `putc` if the port is already selected, causing debug output to also show on HWCDC even when not selected.

cores/esp32/HWCDC.h

@@ -17,16 +17,41 @@
 #if CONFIG_IDF_TARGET_ESP32C3
 
 #include <inttypes.h>
+#include "esp_event.h"
 #include "Stream.h"
 
+ESP_EVENT_DECLARE_BASE(ARDUINO_HW_CDC_EVENTS);
+
+typedef enum {
+    ARDUINO_HW_CDC_ANY_EVENT = ESP_EVENT_ANY_ID,
+    ARDUINO_HW_CDC_CONNECTED_EVENT = 0,
+    ARDUINO_HW_CDC_BUS_RESET_EVENT,
+    ARDUINO_HW_CDC_RX_EVENT,
+    ARDUINO_HW_CDC_TX_EVENT,
+    ARDUINO_HW_CDC_MAX_EVENT,
+} arduino_hw_cdc_event_t;
+
+typedef union {
+    struct {
+            size_t len;
+    } rx;
+    struct {
+            size_t len;
+    } tx;
+} arduino_hw_cdc_event_data_t;
+
 class HWCDC: public Stream
 {
 public:
     HWCDC();
     ~HWCDC();
 
+    void onEvent(esp_event_handler_t callback);
+    void onEvent(arduino_hw_cdc_event_t event, esp_event_handler_t callback);
+
     size_t setRxBufferSize(size_t);
     size_t setTxBufferSize(size_t);
+    void setTxTimeoutMs(uint32_t timeout);
     void begin(unsigned long baud=0);
     void end();