Add support to read parquet file metadata through deephaven

[malhotrashivam]

This will help with remotely debugging and understanding the parquet file structure. We can follow the similar API spec as duck_db: https://duckdb.org/docs/data/parquet/overview

• read_parquet
• parquet_file_metadata
• parquet_kv_metadata
• parquet_schema

[malhotrashivam]

One approach that @rcaudy suggested in the meanwhile:

If you have a raw source table in groovy, you should be able to:

1. .initialize() it
2. Get its columnSourceManager field.
3. Get the Table result of the CSM’s locationTable()
4. Get the K-V metadata for each file by applying an update("KV = ((io.deephaven.parquet.table.location.ParquetTableLocation) _TableLocation).getParquetKey().getMetadata().getFileMetaData().getKeyValueMetaData()")

[devinrsmith]

It may be useful to write a little standalone utility to print out the FileMetaData as JSON; I've found this little script helpful:

        try (final TMemoryBuffer buffer = new TMemoryBuffer(128)) {
            fileMetaData.write(new TSimpleJSONProtocol(buffer));
            buffer.flush();
            System.out.println(buffer.toString(StandardCharsets.UTF_8));
        } catch (TException e) {
            // ignore
        }