lwip: Reference official 2.1.3-esp branch
lwip: Reference official 2.1.3-esp branch

Actual changes against 2.1.3-esp-dev:
* Fix IPv6 zoning violations
* Melted on-demand timer's commits into one

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf