Improve the design of the code sample view

[mansona]

We are trying to standardise the code-sample view for the Ember websites. Currently we have a code-sample that is powered by Prism with a few extra features:

Can be seen on https://guides.emberjs.com/release/components/

There has been some work done on a newer refined design: abstract link but it needs some more work to communicate the clarity of the type of file that you are displaying

We are standardising on using https://github.com/empress/ember-showdown-prism to power all of our websites' code views so the changes to the design should likely go there 👍