refactor: VectorDataReader to classes in TypeHandlers namespace

[coveralls]

Pull Request Test Coverage Report for Build 6615153770

• 285 of 320 (89.06%) changed or added relevant lines in 17 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-1.9%) to 85.121%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
DuckDB.NET.Data/TypeHandlers/BaseTypeHandler.cs	26	27	96.3%
DuckDB.NET.Data/TypeHandlers/DateTypeHandler.cs	13	14	92.86%
DuckDB.NET.Data/TypeHandlers/IntervalTypeHandler.cs	4	5	80.0%
DuckDB.NET.Data/TypeHandlers/StructTypeHandler.cs	28	29	96.55%
DuckDB.NET.Data/TypeHandlers/TypeHandlerFactory.cs	25	26	96.15%
DuckDB.NET.Data/TypeHandlers/BlobTypeHandler.cs	8	10	80.0%
DuckDB.NET.Data/TypeHandlers/NumericTypeHandler.cs	14	16	87.5%
DuckDB.NET.Data/TypeHandlers/TimeTypeHandler.cs	12	14	85.71%
DuckDB.NET.Data/DuckDBDataReader.cs	18	21	85.71%
DuckDB.NET.Data/TypeHandlers/DecimalTypeHandler.cs	35	38	92.11%
<!--	Total:	285	320	89.06%	-->

Files with Coverage Reduction	New Missed Lines	%
DuckDB.NET.Bindings/DuckDBNativeObjects.cs	3	73.26%
<!--	Total:	3		-->

Totals
Change from base Build 6507657818:	-1.9%
Covered Lines:	1013
Relevant Lines:	1160

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💛 - Coveralls