This connects to a postgres server and crafts postgres-protocol message to encode its arguments into postgres' text and binary encodings. The result is printed as JSON "test cases" on standard out. If no arguments are provided, a set of default values for the specified data type will be sent. If arguments are provided, they will be sent as the values.
The target postgres server must accept plaintext (non-ssl) connections from the postgres:postgres account. A suitable server can be started with:
`docker run -p 127.0.0.1:5432:5432 postgres`
The output of this file generates pkg/sql/pgwire/testdata/encodings.json.