fix(pg-protocol): decode binary result fields as raw bytes instead of utf-8

[nigrosimone]

Results requested with binary: true are silently corrupted. No error is raised, the query
succeeds and returns wrong values:

const client = new Client()
await client.connect()

await client.query({ text: 'SELECT $1::int AS a', values: [127], binary: true })
// { a: 127 }    correct

await client.query({ text: 'SELECT $1::int AS a', values: [128], binary: true })
// { a: 239 }    WRONG

await client.query({ text: 'SELECT $1::int AS a', values: [200], binary: true })
// { a: 239 }    WRONG

await client.query({ text: 'SELECT $1::int AS a', values: [-1], binary: true })
// { a: -272646673 }    WRONG