Add babel-plugin-styled-components to all packages

[ChrisBAshton]

Is your feature request related to a problem? Please describe.

You should definitely use the styled-components Babel plugin.

While removing it doesn't break anything, it makes development a lot nicer by putting the component names into the generated classes, improves performance in production, and enables support for features like the css prop!

See #105 (comment) (thanks, @mxstbr!)

Not all of our packages use babel-plugin-styled-components. As a general rule, we should be adding it to all components (see #162). The components that don't use it will need updating so that they use it, and the snapshot tests will need updating as the class names will be different.

Testing notes
[Tester to complete]

Dev insight: Regression test only.

• Initially labelled with "Refinement needed"

[ryanmccombe]

This seems to have already been done: fcea0b5

The issue talks about "adding it to all components" and "updating components that don't use it" - I'm not sure what that means in the context of a babel plugin?

It is configured in the .babelrc at the root of the directory, and is getting used by every styled component:

This issue seems like it should be closed