(a1.0.9 - 24w07a) Pause menu background

[muzikbike]

The translucent, dark background used for the pause menu was hardcoded in this version range, but as of 24w09a it uses a texture file, which is also lighter. It might be advisable to add functionality to MC-TextureGen that creates a texture file that can be added to a resource pack to produce a visually identical result to the pre-24w09a game menu.

[muzikbike]