Add a Parquet file with column chunk key-value metadata

[clee704]

This file has a single row group with 0 row and 2 columns.

The first column chunk has the following key-value metadata:

• The first entry has a key "foo" mapped to a value "bar".
• The second entry has a key "thisiskeywithoutvalue" and does not have a value.

Created with this code, with a modified Arrow library to output "thisiskeywithoutvalue" without a value for the first column.

PARQUET_ASSIGN_OR_THROW(auto sink,
                        arrow::io::FileOutputStream::Open(
                            "column_chunk_key_value_metadata.parquet"));
auto writer = parquet::ParquetFileWriter::Open(
    sink, std::static_pointer_cast<parquet::schema::GroupNode>(
              parquet::schema::GroupNode::Make(
                  "schema", parquet::Repetition::REQUIRED,
                  {parquet::schema::PrimitiveNode::Make(
                       "column1", parquet::Repetition::OPTIONAL,
                       parquet::Type::INT32),
                   parquet::schema::PrimitiveNode::Make(
                       "column2", parquet::Repetition::OPTIONAL,
                       parquet::Type::INT32)})));
auto rg_writer = writer->AppendRowGroup();
rg_writer->NextColumn()->key_value_metadata().Append("foo", "bar");
rg_writer->NextColumn();

This is for apache/arrow#41580

[wgtmac]

Would you mind adding some description about this new file in the README?

[pitrou]

Suggestion: add two metadata entries: one with a value, the other without (the metadata key is mandatory while the value is optional).

[mapleFU]

Merged, thanks!