[WIP: Do not review] NanoVDB: VoxelBlockManager CPU port of decodeInverseMaps #4381

Job	Run time
linux-ax:2026-cxx:clang++-Debug	20m 1s
linux-ax:2026-cxx:g++-Release	3m 59s
linux-ax:2023-clang15-cxx:clang++-Release	3m 54s
linux-ax:2025-clang19.1-cxx:clang++-Release	4m 23s
macos-cxx:clang++-llvm:18-Release	12m 10s
macos-cxx:clang++-llvm:20-Release	17m 48s
macos-cxx:clang++-llvm:17-Release	19m 0s
linux-ax:2024-clang16.2-cxx:clang++-Release	3m 58s
macos-cxx:clang++-llvm:21-Release	14m 42s
macos-cxx:clang++-llvm:19-Release	14m 26s
linux-ax:2026-cxx:clang++-Release	4m 6s
macos-cxx:clang++-llvm:16-Release	12m 45s
macos-cxx:clang++-llvm:21-Release	17m 58s
gen-grammar	-6s
	2h 29m 4s

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