backports HWCDC to v2.0.15 (espressif#9462)

* feat: backports HWCDC

* fix: statement order

* feat: Apply suggestions from code review

* Create HWCDC_Events.ino

* Create .skip.esp32

* Create .skip.esp32s2

* Delete libraries/ESP32/examples/HWSerial_Events/.skip.esp32s2

* Delete libraries/ESP32/examples/HWSerial_Events/.skip.esp32

* Delete libraries/ESP32/examples/HWSerial_Events/HWSerial_Events.ino

Author: SuGlider