Add option to get result as an object, and not as a formatted text

[bahmutov]

Right now we are getting the result as text, something like this

command: npm run find:standard
  code: 0
  failed: false
  killed: false
  signal: null
  timedOut: false

  stdout:
  -------
  > nested@1.0.0 find:standard /Users/gleb/git/bin-up/test/nested
  > $(../../bin/bin-up standard)
  -------
  stderr:
  -------
  Found /Users/gleb/git/bin-up/node_modules/.bin/standard
  -------

it would be nice to sometimes get results from execa-wrap straight from execa