Allow to return arbitary data from the computed data property

[dweidner]

Is your feature request related to a problem? Please describe.
I was a bit surprised to find out, that it is only possible to return string values from the computed data property. I expected the new feature to apply the magic string substitution only to string values and to leave other data types alone. Here a short example what I tried to do:

// ./src/pages/pages.11tydata.js
module.exports = {
  layout: 'page',
  eleventyComputed: {
    isHomePage ({ slug }) {
      return slug === 'home';
    },
    slug ({ page, slug = null }) {
      return slug || page.fileSlug;
    },
    permalink ({ slug, isHomePage = false }) {
      return isHomePage ? '/' : `/${slug}/`;
    }
  }
};

Describe the solution you'd like
It would be great, if I could return any data type from the computed data functions not only string value. I could think of other use cases, where this might be helpful:

module.exports = {
  layout: 'page',
  eleventyComputed: {
    seo ({ page }) {
      return {
        title: '…',
        description: '…',
        author: '…'
      };
    }
  }
};

Describe alternatives you've considered
In my example it would be easy to move the condition into the permalink function directly, but then the boolean would not be available within the template files.

[zachleat]

This will ship with 0.11.0 beta 4