Set global.InventoryWindow_defaultGetTexture for inventory-window

Refactoring to make item texturing codepaths cleaner, less intertwined.

Requires all these commits:
deathcap/inventory-window@0c9f608123dfd6596891282a0a53249e42af2645
deathcap/voxel-workbench@d6a6ca1ed6d913072c99ce32b1b01cdc9f603469
deathcap/voxel-inventory-hotbar@ce194714d7288c9cb2eaf8f097d7049583c6841e
deathcap/voxel-inventory-dialog@f44eed1af728181deecd4d9550a7bbbfb5e503be
Move workbench block & recipe registration to voxel-workbench

deathcap/voxel-workbench@ffe896e78a46a5127d2d1b51a4b6d206c4e4fed2
Let voxel-workbench handle opening its GUI

Requires deathcap/voxel-workbench@d85cb990095147f93ac25bb78f0dfe22a641833f