Detach allow list data from permissioning contract

[MadelineMurray]

When the permissioning smart contract is upgraded, the allow list entries must be reloaded into the upgraded contract. Detaching the data in a way that allows the contract to be upgraded without losing the data would be a better user experience.

[vmichalik]

Detaching the data will help to pave the way for creating a migration path to upgrade Permissioning SCs

[vmichalik]

this is a decent explanation of the advantages of keeping storage in a separate contract https://fravoll.github.io/solidity-patterns/eternal_storage.html

h/t @macfarla