support JSON columns in Postgres

[czue]

This adds support for Postgres JSON column types. This is particularly useful if you want to use the DET to generate a "data lake" by exporting the entire contents of e.g. the "form" property.

I was shocked how easy this was. Only one little quirk to chase down with type compatibility.

[snopoke]

Confirm that this only works if you explicitly specify the data type in the query file.

[czue]

Confirm that this only works if you explicitly specify the data type in the query file.

Correct. Was going to mention that in docs. I guess we could add a command-line flag to do this automatically or something, but guessing explicit is fine for now?

Let me know if you think it's worth adding a test that it doesn't change behavior without the type

[snopoke]

Confirm that this only works if you explicitly specify the data type in the query file.

Correct. Was going to mention that in docs. I guess we could add a command-line flag to do this automatically or something, but guessing explicit is fine for now?

Yes, I think this should be explicit rather than creating JSON columns for incorrect query files.

[snopoke]

Let me know if you think it's worth adding a test that it doesn't change behavior without the type

Don't think it's necessary

[proteusvacuum]

This is great!