* chore: bump nan to 2.23.0
* Fix C++ flags passed to C compiler in NAN spec runner
Passing C++-specific flags to the C compiler caused failures building native test modules.
NAN uprgaded the version of node-gyp it uses, triggering a new codepath with the C compiler that didn't occur before. In that new branch, the C++ flags present in the CFLAGS environment variable we were passing in caused the C compiler to error out:
```
error: invalid argument '-std=c++20' not allowed with 'C'
```
The fix is to only pass C++-specific flags to the C++ compiler, and not the C compiler. This is done by separating out the CFLAGS and CXXFLAGS environment variables in our nan-spec-runner.js script.
I'm curious to know more about why each of these flags are necessary, but for now this change restores the previous behavior where native test modules could be built successfully.
* test: use v8 version check instead of node version check (patch)
* Re-enable `methodswithdata-test`
418b8235bc