Add parquet format

[peauc]

Describe the problem to be solved

As of today in grist there are a few supported import/export formats as per this document
Adding parquet would be great as it is becoming prevalent in the ML community and has great performances in compression as well as predictable data types.

Describe the solution you would like

Adding parquet as a supported import/export format

[simonaubertbd]

+1 here, parquet becomes de facto the standard file format in the data analysis, from Hadoop to ML.

Best regards,

Simon