There are lots of places where HashTable is used with
AllocatorWithStackMemory, but the size of allocator inline memory is set
incorrectly, and it's less than the initial HashTable buffer size.
Because of this, HashTable is always allocated on the heap, and the
inline memory becomes a useless dead weight.

For PODArray, we have previously added a helper template that makes sure
these values are in sync, so there was only one such discrepancy left,
in the unit test.

* Move some code outside dbms/src folder
* Fix paths

This is the first step of allowing heterogeneous cells in hash tables.

performance test results are

```

1. HashMap<UInt16, UInt8, TrivialHash, HashTableFixedGrower<16>>;
2. NewLookupMap<UInt16, UInt8>

ResolutionWidth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................223550276.46
ResolutionWidth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................248772721.24
Best: 2 - 24877272124

ResolutionWidth 100000 1 ..........................................................................................................................................................................................................................................................238498413.99
ResolutionWidth 100000 2 ..........................................................................................................................................................................................................................................................261808889.98
Best: 2 - 26180888998

ResolutionWidth 300000 1 ...................................................................................239307348.81
ResolutionWidth 300000 2 ...................................................................................257592761.30
Best: 2 - 25759276130

ResolutionWidth 1000000 1 .........................240144759.26
ResolutionWidth 1000000 2 .........................257093531.91
Best: 2 - 25709353191

ResolutionWidth 5000000 1 .....241573260.35
ResolutionWidth 5000000 2 .....259314162.79
Best: 2 - 25931416279

ResolutionDepth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................217108119.84
ResolutionDepth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................249459504.41
Best: 2 - 24945950441

ResolutionDepth 100000 1 ..........................................................................................................................................................................................................................................................229065162.17
ResolutionDepth 100000 2 ..........................................................................................................................................................................................................................................................253769105.64
Best: 2 - 25376910564

ResolutionDepth 300000 1 ...................................................................................233079225.18
ResolutionDepth 300000 2 ...................................................................................256316273.78
Best: 2 - 25631627378

ResolutionDepth 1000000 1 .........................234184633.51
ResolutionDepth 1000000 2 .........................261100491.57
Best: 2 - 26110049157

ResolutionDepth 5000000 1 .....233118795.66
ResolutionDepth 5000000 2 .....252436160.41
Best: 2 - 25243616041

```

Field f;

before:

f = Int64(-42);

after:

f = -42;