Remove accent color

[nathan-schmidt-viget]

Originally, we thought that the accent color would come in really helpful. But for the first two projects, we have just removed it as the designs required more colors than just one, or we needed more flexibility then the current accent color provided.

We would remove the accent color from:

• theme.json
• TW config
• TW button.js May need to do a search to see if it is anywhere else.

[nathan-schmidt-viget]

@bd-viget I think we can close this down as you removed it before TTT.