Allow communities to use other currencies

[obernardovieira]

Is your feature request related to a problem? Please describe.

Currently, every community uses cUSD.

Describe the solution you'd like

Every community should be able to select a currency to use.
It should also be possible to change the currency at any moment. Changing the currency should swap existing balance of the community with the new currency.

Additional context

This allowed currencies should be governable by the DAO.
Make sure this currencies addresses are upgradable by the DAO, converting all funds.