Testimonial: Add author (2.2.x)

Problem/Motivation

This ticket is to expand on the Testimonial component.
We want to add the ability to have a picture for the Author.

So steps will be

1. Create a new image field for the author.
2. Add it in the twig template, and theme with SCSS accordingly.

Attached is what we're going for.

Notes:
There is an image field already there, along with an image position.
There should be login in the TWIG template, so that if no image is uploaded, then the text takes up the whole space.
And if there is an image, keep functionality as is, and simply add the author image beside the name and role.