[WIP] Zero padding on MemTiles #6103

Job	Run time
ubuntu-22.04 llvm assert=ON rtti=ON	5m 34s
ubuntu-22.04 llvm assert=ON rtti=OFF	5m 8s
ubuntu-22.04 llvm assert=OFF rtti=ON	5m 13s
ubuntu-22.04 llvm assert=OFF rtti=OFF	5m 4s
ubuntu-22.04 gcc assert=ON rtti=ON	5m 7s
ubuntu-22.04 gcc assert=ON rtti=OFF	4m 57s
ubuntu-22.04 gcc assert=OFF rtti=ON	5m 12s
ubuntu-22.04 gcc assert=OFF rtti=OFF	5m 16s
ubuntu-24.04 llvm assert=ON rtti=ON	5m 44s
ubuntu-24.04 llvm assert=ON rtti=OFF	5m 10s
ubuntu-24.04 llvm assert=OFF rtti=ON	5m 10s
ubuntu-24.04 llvm assert=OFF rtti=OFF	5m 12s
ubuntu-24.04 gcc assert=ON rtti=ON	5m 2s
ubuntu-24.04 gcc assert=ON rtti=OFF	5m 2s
ubuntu-24.04 gcc assert=OFF rtti=ON	4m 57s
ubuntu-24.04 gcc assert=OFF rtti=OFF	5m 15s
ubuntu-20.04 gcc-11 assert=ON rtti=OFF	5m 18s
ubuntu-20.04 gcc-11 assert=OFF rtti=OFF	5m 42s
ubuntu-20.04 gcc-11 assert=ON rtti=ON	5m 38s
ubuntu-20.04 gcc-11 assert=OFF rtti=ON	5m 27s
windows-2019 msvc assert=ON rtti=ON	8m 54s
windows-2019 msvc assert=ON rtti=OFF	7m 26s
windows-2019 msvc assert=OFF rtti=ON	8m 15s
windows-2019 msvc assert=OFF rtti=OFF	8m 26s
	2h 18m 9s

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