Update Polish translations. (#7525)

* Sync pl.po to source code.
* Fix "U.S. Sales" translation.
* Change "żywotność" to "witalność" so it flows better in character stats screen.
* Button combo bindings translation.
* Player inspection translations.
* Debug commands translations.
* Inventory sorting translations.
* Quick spell translations.
* Chat log translations.
* Consistent translations for "armor" and "armor class".
* Update store label translations.
* Different take on resists translation on character screen.
* Shorten Experience translation to avoid overflowing.
* Improve the validate_translations.py script.