feat: allow hilbish.run to take a table of files to use for output

[TorchedSammy]

this makes it possible to pipe commands to any output via lua api

usage example:

local fs = require 'fs'

local output = io.open('output.txt', 'w')

hilbish.run('ls', {
    out = output,
    err = output
})

closes #174 since this pr also introduces the pipe function

• [x] I have documented changes and additions in the CHANGELOG.md.