Adding foundations section

- Adding Foundation section with colours page
- Adding theme colours page
- Adding the relevant css and ability to do so.
- Remove typography and icons (to be pushed to another PR)

Author: zoharma

.storybook/preview.tsx

@@ -69,6 +69,11 @@ const preview: Preview = {
           "Installation",
           "Practical Guidance",
           "Working with Components",
+          "Foundations",
+          "Foundations/Theme Colours",
+          "Foundations/Colour",
+          "Foundations/Typography",
+          "Foundations/Icons",
           "Helpers",
           "Theme",
           "Theme/Logos",