`csv-stringify/sync` does not output headers when input is an empty array

[alexstrat]

Describe the bug

Even if used with header: true and columns options, csv-stringify/sync does not output headers when input is an empty array.

The stream or callback API does.

To Reproduce

const { stringify } = require('csv-stringify/sync')

stringify([], { header: true, columns: ['foo', 'bar']})
// ❌ returns '' 
// expected 'foo,bar'

const { stringify } = require('csv-stringify')
stringify([], { header: true, columns: ['foo', 'bar']}, (e, content) => console.log(content))
// ✅ logs 'foo,bar'