WGPU: Create cube textures with one layer per face #273

Job	Run time
build (windows, x86_64, msvc, Debug)	1m 6s
build (windows, x86_64, msvc, Release)	1m 45s
build (windows, aarch64, msvc, Debug)	2m 7s
build (windows, aarch64, msvc, Release)	2m 30s
build (linux, x86_64, gcc, Debug)	35s
build (linux, x86_64, gcc, Release)	36s
build (linux, x86_64, clang, Debug)	1m 5s
build (linux, x86_64, clang, Release)	1m 21s
build (linux, aarch64, gcc, Debug)	1m 22s
build (linux, aarch64, gcc, Release)	1m 27s
build (linux, aarch64, clang, Debug)	1m 20s
build (linux, aarch64, clang, Release)	1m 13s
build (macos, aarch64, clang, Debug)	1m 8s
build (macos, aarch64, clang, Release)	1m 15s
	18m 50s

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