Backoffice Product List table user interface uplift

I think this decision of whether to use or avoid the css-in-js pattern is really critical.

As a bit of background, if we decide to go down that road; anyone that wanted to change some simple CSS styles would have to read this document and understand it all before they could make any CSS changes: https://material-ui.com/customization/components/

And that applies to both our current dev team and any potential first-time contributors…