refactor the Care card component and make it a variant of the Card component

[adam-the]

see nhsuk/nhsuk-frontend#746

I'd like to work on this but I have one question first:
Should feature cards also be included in the card's type parameter? They seem to be mutually exclusive in the nunjucks template, so having all variants, excluding the clickable modifier, in the type parameter makes sense to me.

Doing it this way would seem to go against #68

[KaiSpencer]

Hi @ItsiAdam,
Personally i agree with the type parameter implementation, although Its not something I've had a look at yet given me and @Tomdango currently focusing on v5 parity before any v6 changes which this falls under.

[jakeb-nhs]

This has now been addressed as part of the latest release: https://github.com/NHSDigital/nhsuk-react-components/releases/tag/v4.0.0
Care cards are no longer a standalone component and use the cardType prop