feat: add iso date formatter

[antongolub]

export const formatIsoLocaleString = (date: Date): string => {
  const tzo = -date.getTimezoneOffset()

  const dif = tzo >= 0 ? '+' : '-'

  const pad = (num: number): string => {
    const norm = Math.floor(Math.abs(num))
    return (norm < 10 ? '0' : '') + norm
  }

  return date.getFullYear() +
    '-' + pad(date.getMonth() + 1) +
    '-' + pad(date.getDate()) +
    'T' + pad(date.getHours()) +
    ':' + pad(date.getMinutes()) +
    ':' + pad(date.getSeconds()) +
    dif + pad(tzo / 60) +
    ':' + pad(tzo % 60)
}