Overview

Update to the latest Pico-SDK 2.2.0 release and clean up and rationalizes the Platform.IO infrastructure.

SDK 2.2.0 "kitchen sink" update

Update to Pico-SDK 2.2.0 release, remove multi-lib LWIP, clean up CMake, clean up P.IO build hardcoded defines (#3049)
Add LIB_PICO_MULTICORE to libpico build
Fixes #3058 and behavior of async_context in multicore apps
Update and clean up the libpico CMakefile and common platform_def.txt. Use platform_def files for p.io builds
Use a common text file that GCC and P.IO can parse to set defines for the build, ensuring Arduino and P.IO stay in sync.
Link to config include files, don't copy, where possible to keep things sane.
Re-enable BOOT2.S compiles in libpico (no change to .S outputs)

Update LittleFS to latest release 2.11.1
Build LWIP at app compile time, no need for multi
We needed about 6 copies of the LWIP/BT library for each CPU when the LWIP library was built as part of the SDK libpico.
Remove LWIP from the SDK builds and replace it with the actual LWIP source (linked via #include) so we can adjust for IPv4/IPv6/32K/16K at runtime. Shrinks download and install size of a release significantly. Still needs separate LWIP-BT library because the CYW43 driver is different when BT is enabled.