Travis CI: add Windows support

[php-coder]

In order to prevent regressions on Windows it's suggested to configure CI to execute our checks under that OS. We can run them periodically rather than on every build.

See also: https://docs.travis-ci.com/user/reference/windows/

The list of issues/regressions that could be caught by that:

• Jdbc*DaoTest fail under Windows (#1164)
• CodeNarc fails on Windows with AssertionError (#994)
• integration tests were failing because of line endings (d14bb06aea779c124738b3c7c4b122e35f6b77e6)
• CheckStyle was failing because of line endings (6791512302782910d3f309ba1fef784ad82e41fb)
• CheckStyle warnings weren't suppressed on Windiows (e15abf3e8434e5a7ccd9adcf0b305551f5d0a3d3)

[php-coder]

Here is how to run periodically in GitHub Actions: https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule or manually: https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#workflow_dispatch