WADS: sky textures

 sky textures by me based on ones i made for librequake but still currently in a draft lavenderdotpet/LibreQuake#130

were made with the help of millenia3d who was/is helping me learn substance designer

Co-Authored-By: Azure Midsummer <122748514+azure-midsummer@users.noreply.github.com>

Author: lavenderdotpet