usb_serial_jtag: support usb_serial_jtag on esp32c3

USB serial/jtag controller: Add vfs (logging/printf), panic handler, gdb support.

See merge request espressif/esp-idf!12925

components/esp_gdbstub/src/packet.c

@@ -64,6 +64,7 @@ void esp_gdbstub_send_end(void)
 {
     esp_gdbstub_putchar('#');
     esp_gdbstub_send_hex(s_chsum, 8);
+    esp_gdbstub_flush();
 }
 
 // Send a packet with a string as content