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PARQUET-1772: [C++] ParquetFileWriter: Data overwritten in append mode

Detect when the output stream provided is in append mode and raise an
exception.  This is done to prevent existing data being overwritten as
Parquet does not yet support appending data to existing files.

Closes #6228 from gawain-bolton/PARQUET-1772_give_error_for_append and squashes the following commits:

5399cfb9f <gawain.bolton> Fix TestParquetFileFormat.ScanRecordBatchReaderProjectedMissingCols unit test in arrow-dataset-file-parquet-test
ed4b2b4a6 <Wes McKinney> Fix Arrow unit tests
ec3bd42bf <gawain.bolton> PARQUET-1772:  ParquetFileWriter: Data overwritten in append mode

Lead-authored-by: Gawain Bolton <gawain.bolton@cfm.fr>
Co-authored-by: gawain.bolton <gawain.bolton@cfm.fr>
Co-authored-by: Wes McKinney <wesm+git@apache.org>
Signed-off-by: Wes McKinney <wesm+git@apache.org>