Draft: perf(allocator): use mimalloc allocator to improve performance

According to the flamegraphs we have seen, allocations take significant amount of time during SQL query execution. This commit replaces standart allocator with mimalloc (https://github.com/microsoft/mimalloc) which showed notable performance improvements on syntetic tests (the one from ./stress-test).

I have also tried jemalloc and my results were the following:

std 9468.993324/s jemmaloc 10323.862407/s mimalloc 12140.168513/s

So mimalloc is chosen as the most promising candidate.