Fix Python3 tool on Windows

[cskrisz]

Remove the file python37._pth from the python3 tool folder to allow scripts to import any modules.

Closes: #6988, #6979, #6984, #7066

[ZeroAurora]

If python is already installed by vcpkg before, after this PR is merged, should users remove python37._pth manually?

[cskrisz]

I didn't realize vcpkg is already trying to stay backward compatible with old installations. For example, some portable tools won't even get updated if they have already been installed.

[ZeroAurora]

So should a warning be set? Or a function to delete python37._pth?

[cskrisz]

No, the underlying problem regarding the update process of tools should be addressed. That's not necessarily complicated, every tool ${SUBDIR} should contain a version number and for cases like this, we could append a revision number.

[cskrisz]

I made the changes for python3 and added the version to SUBDIR as I see some other tools have already done this.

[vicroms]

@cskrisz

Thanks for the PR!

I tested all ports using PYTHON3 in PR #7133.
Only open62541 needed some fixes.