test: cover path.basename when path and ext are the same

In path.basename was a case when the path
and the extension is the same and this wasn't
covered with tests.

I covered this case both in Windows and Unix environments.

PR-URL: https://github.com/nodejs/node/pull/24570


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>