[epic] Initial cohort of group policies

[benjaminbollen]

We can write and deploy one or more (reusable) group policies onchain. Then to create a new group one needs an EoA or a SAFE contract, register as a group in hub v2, and trust from SAFE/EoA avatars (human or groups).

Preliminary tasks:

• setup new circles-groups repository #3

List of possible policies (which disable path transfer-mint explicitly):

• only trusted humans can mint (even if groups are also trusted collateral, but groups can't call mint themselves) #1