Add visibility field for commons

We should add for each common\project a parameter in the governance to indicate the "visibilityToNonMembers".
The options are: onlyAbout, aboutMembers, aboutMembersWallet, aboutMembersWalletFeed, aboutFeed.
I wrote it as it is one parameter but we can also use several parameters for this, as you prefer.
This will impact in the future which sections of the common will be visible to non-members.
The default option for now should be onlyAbout.
We should also migrate existing commons to include this parameter with onlyAbout.