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PARQUET-1799: [C++] Stream API: Relax schema checking when reading

The converted type expected by the StreamReader may not match with
that found in the Parquet file schema in the following cases:

C++ type | StreamReader expected converted type | Parquet file converted type
-------------|-------------------------------------------------------|------------------------------------
int32_t     | INT_32         | NONE or DECIMAL
int64_t     | INT_64         | NONE or DECIMAL
std::string | UTF8           | NONE

A set of these exceptions is created to allow for these cases when the
StreamReader and Parquet file schema converted types do not match
exactly.

Closes #6434 from gawain-bolton/PARQUET-1799_stream_api_relax_schema_checking and squashes the following commits:

9fb8935a2 <gawain.bolton> Updates after review by Antoine Pitrou on 20200217
5756b08d4 <gawain.bolton> PARQUET-1799:  Stream API: Relax schema checking when reading

Authored-by: gawain.bolton <gawain.bolton@cfm.fr>
Signed-off-by: Antoine Pitrou <antoine@python.org>