Improved matching enum data types to protobuf enum type.
Fixed serialization of the Map data type.
Omitted values are now set by default.

(for CSV, TSV, JSON formats)

  * for CSV and TSV input formats input_format_csv_enum_as_number,
    input_format_tsv_enum_as_number settings should be enabled in order to
    treat input value as enum id

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

 * value_type => ValueType for ColumnVector and ColumnDecimal
 * minor formatting fixes
 * removed `extern template`

Instead, these methods return a pointer to the required data as they are
stored inside the hash table. The caller uses overloaded functions to
get the key and "mapped" values from this pointer. Such an interface
avoids the need for constructing iterator-like wrapper objects, which is
especially important for compound hash tables such as the future
StringHashMap.

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

```