Aims to fix #28600
This is a spike for now, and will need to have the CSS moved, but I wanted to see how feasible this could be. Unfortunately the standard .form-control needs the small spinner, so we could support a large input but I'm unsure how to handle smaller inputs. An even smaller spinner?
Would love thoughts from @twbs/css-review.
Preview: https://deploy-preview-29107--twbs-bootstrap.netlify.com/docs/4.3/components/spinners/#with-inputs