* Remove Pico-SDK C++ exception-override new/delete
We support exceptions on and off, but the cxx_options file in the
SDK implemented a single override to new/delete.
Remove it so we will use GCC's build-in operator new/delete
which will be correct for either option (2 different libstdc++
versions are shipped as part of the toolchain).
* Remove duplicated SDK files
The SDK will link in the same compilation unit in the LWIP builds.
Remove them to shrink the repo size by ~28MB.
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