Create a series of layout components for the MainStage

[OneOneFour]

As of the current version of the site we have a set of "Hotspot" components which allow developers to put content such as graphs or supplemental text in nice well defined locations. We do not however currently have a nice system for laying out the core content present in the main stage of the visualization and it would be great to have these.

Some components that could fit into this mold could be based on CSS grid:

• A 2x2 grid for placing in four different animated items
• A center spot component that a single graph/plotly/p5/canvas element directly in the centre of the screen
• A "main & stack" layout featuring a single element taking up 3/4 of the horizontal space and then a vertical stack of smaller sub elements on the right/left hand side

(I will attach an image of these ideas in due course)