Add support for the "Raspberry Pi Pico/RP2040/RP2350" boards platform

[generationmake]

The 3rd party "Raspberry Pi Pico/RP2040/RP2350" boards platform (https://github.com/earlephilhower/arduino-pico) is a popular alternative to the "Arduino Mbed OS RP2040 Boards" platform.

Raspberry Pi Pico/RP2040/RP2350 brings its own lwIP stack and this conflicts with the builtin lwIP stack of this library.

I would like to make a pull request which deals with this issue and uses the lwIP stack of Raspberry Pi Pico/RP2040/RP2350.
Are you fine with this?

[bnarit]

I have successful use this lib on RP2350, you can check on my post in this repository. However, the TCP is still on hold , as well as webserver.

There are some tricks that need to be done, and you will be able to use this lib on rp2350.