Store as unique ptr #1147

Job	Run time
Linux [UBSAN] [lmdb \| clang]	39m 41s
Linux [ASAN] [lmdb \| clang]	38m 2s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	37m 35s
Linux [TSAN] [lmdb \| clang] (Errors Ignored)	38m 11s
Linux [LEAK] [lmdb \| clang] (Errors Ignored)	37m 13s
Linux [UBSAN] [rocksdb \| clang]	45m 3s
Linux [ASAN] [rocksdb \| clang]	47m 30s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	49m 12s
Linux [TSAN] [rocksdb \| clang] (Errors Ignored)	1h 32m 47s
macOS [UBSAN] [lmdb \| clang]	28m 53s
Linux [LEAK] [rocksdb \| clang] (Errors Ignored)	50m 55s
macOS [ASAN] [lmdb \| clang]	25m 9s
macOS [TSAN] [lmdb \| clang] (Errors Ignored)	25m 17s
macOS [UBSAN] [rocksdb \| clang]	33m 30s
macOS [ASAN] [rocksdb \| clang]	29m 39s
macOS [TSAN] [rocksdb \| clang] (Errors Ignored)	41m 59s
	11h 0m 36s

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