fix: use platform dependent path for join, resolve, and parse

[danielroe]

This takes advantage of the fact that win32 handles both \ and / as valid separators and therefore can operate safely on a posix path.

1. resolves Resolve behavior #2 by using path.win32 (resolve)
2. handles unc paths by using path.win32 (join)
3. resolves a parse issue where the drive letter was being stripped on windows
4. normalizes toNamespacedPath as well, for consistency

An observation: this entire library works (passes tests) in reverse using path.win32 and normalising the result (as with 1 & 2 above)

With this PR merged, #3 should be passing.

[pi0]

Comparing win32 implementation of resolve to the POSIX one there seems a huge difference (and performance impact). In the meantime:

• I think we can use platform dependant behavior for resolve/join, hoping no one cross runs windows paths in posix env
• In the longer term, either inline posix.resolve implementation to apply fixes or directly wrap. Since we do not need ALL windows features in a cross-env implementation.

[pi0]

This is also a platform-dependent API that POSIX behavior is to return input as-is....

[pi0]

I had to revert b90fdaf since seems added edge cases went more :( Let's try when merging test suite for better solution.