Fix PHPCS - PHPSTAN - CSPELL - ESLINT issues

Finally I was able to fix all the PHPSTAN / PHPCS / STYLELINT issues after deleting a lot of uneeded code, needs some extra testing, I'll put it to "Needs Review" for now, but it's futile because we need the ubecart module to be upgraded to D10/D11 which ain't gonna happen soon I guess.

I'll merge to the main branch then.

Automatically closed - issue fixed for 2 weeks with no activity.