`styled-components` Context Provider (CSS Framework deprecation)

[hxltrhuxze]

As we are moving the Design System to Styled Components, we should look to deprecate the CSS Framework package. In order to do so, we should create a <ContextProvider> component that wraps applications using the RNDS. This provider would contain everything in the CSS framework that isn't currently covered by Styled Components.

Acceptance criteria

• [x] Investigated usage of utility classes in downstream applications
• [x] <ContextProvider> component created, containing:
  • [x] @font-face rules to load Lato
  • [x] Resets
  • [x] Base styles (Normalize)
• [x] CSS Framework marked as Deprecated

[thyhjwb6]

My suggestion is that we break this into three separate parts so we could investigate and deprecate first and then implement the main change after.

[m7kvqbe1]

We have broken the context / theming part of this out into a separate ticket: https://github.com/Royal-Navy/design-system/issues/2351