refs https://github.com/TryGhost/Team/issues/1310
We want to use parts of the "Brand setting" form in a separate streamlined settings screen after site setup but that wasn't possible without a lot of duplication.
- extracted individual form fields into separate components for re-use
- included minor refactors like using `uploader.registerFileInput` and `uploader.triggerFileDialog` instead of continually duplicating the same file input trigger method
- fixed accessibility issues
- changed input titles from `<div>` to `<label>` and associated with the component's input fields
- changed `<img {{on "click" upload}}>` to `<input type="image">` so they act as proper buttons and are linked to the label (required a styling change so `img` and `input[type="image"]` are treated equally)
- finished cleanup of `.description-container-labs` by renaming to `.description-container`
