We should document the design details of the new icons in the component library, and in dev docs.

Including rule-set used for BBB, which should be applied consistently:

So here's what I propose as a 'rule-set' to deciding background colours:

1. We allow the actual icon to use the brand colours (so the darker blue in case of BBB).
2. Ideally all plugin icons use the category assigned background colours. For BBB, which would fall in the communication (or maybe collaboration) category, this means green.
3. If the assigned background colour would compromise the branding of the plugin too much, then the plugin will use the default background colour of grey