User level permissioning specification

In the permissioning specification we developed a system to allow data-servers to provide platforms with broad scopes like ReadEnterprises to cover all of the enterprises data on a server.

In ticket projets/projets-clients/open-food-network/data-permissioning-module#40 (closed) we identified that we will need to allow individual users to grant individual users permissions on their data.

Requests to access such permissions may be triggered when Alice tries to access some data from Bob's enterprise. Bob will then need to approve or deny access.

The output of this ticket will be documentation and an itemised plan, similar to the output of the platforms specification linked above. Please also expand the network diagrams of the platform.