fs: fix realpath{Sync} on resolving pipes/sockets

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

fs

Currently

echo "" | node -e "require('fs').realpath('/dev/stdin', console.log)"

and

echo "" | node -e "console.log(require('fs').realpathSync('/dev/stdin'))"

are broken due to our logic of realpath and this patch changes node in a way to match python:

echo "" | python -c "import os; print(os.path.realpath('/dev/stdin'))"