gh-156035: Validate pathlib rename and replace targets before filesystem changes

[lpyu001]

Validate targets before modifying the filesystem so invalid bytes paths raise TypeError without moving the source.

• Issue: pathlib.Path.rename() and replace() may move a file before rejecting a bytes target #156035

[aisk]

For a target with a trailing slash like 'foo/bar/', the OS currently raises NotADirectoryError, but with this change the slash is stripped during normalization, so rename() silently succeeds and replace() may even silently overwrite an existing file.

[aisk]

Maybe we can use this:

def rename(self, target):
    if hasattr(target, 'with_segments'):
        result = target
    else:
        result = self.with_segments(target)
    os.rename(self, target)
    return result