Add option for batch insert

Based on https://node-postgres.com

There are a few different approaches to consider:

Copy streams: https://github.com/brianc/node-pg-copy-streams

Multiple executes:

CREATE TABLE person (
  id SERIAL PRIMARY KEY,
  name TEXT,
  age INTEGER
);

--

PREPARE insert_person_plan (text, integer) AS
INSERT INTO person (name, age)
VALUES ($1, $2);

BEGIN;
EXECUTE insert_person_plan('Alice', 25);
EXECUTE insert_person_plan('Bob', 30);
EXECUTE insert_person_plan('Charlie', 35);
COMMIT;

{
	"execute": {
		"insert_person_plan": [
			["Alice", 25],
			["Bob", 30],
			["Charlie", 35],
		]
	}
}

--

DEALLOCATE insert_person_plan;

SELECT * FROM person;

DROP TABLE person;

The issue provides no file or test entry point. Start by comparing the proposed copy-streams approach with multiple prepared executes, using the node-postgres and node-pg-copy-streams references, then define the supported batch-insert behavior and acceptance tests before implementation.