Arrangement of themes(groups) on home page

[ddy1234]

The appearance of groups on the home page is currently tied to groups having (non-private) datasets tied to them, with seven groups being arranged equidistant, and any datasets over this number appearing below them in the centre.

This has resulted in limitations over the number of themes we can have without potentially negatively impacting the look of the front page. It also means we can't manually control the themes appearing on the front page.

As a future addition - would we be able to change this to allow for fixed groups on the front page? Either as a one-time addition of fixed groups on the page, or through control of this mechanism on the back-end ourselves.