Create a better component that shows all of the shades and tints for a colour

[mansona]

Currently on the "Colours" page in the documentation, we have a single "Colour Pallet" display for each different shade of grey (grey-100 through grey-900). This makes the page a bit too bulky and hard to use, especially when we start adding new secondary colours (see #305)

We need to add a component that can display a full range of shades/tints of a colour while still showing the accessibility grading of the different text colours and sizes with that as a background 👍

This is likely to be something that will need to be added upstream in Field Guide