[New VM] Organize `contrib` crate (or module) in the new VM SDK

[devendran-m]

Organize a “contrib” crate (or module) in the new VM SDK that contains a bunch of useful traits for smart contract devs that are ready to use. Some of the code mentioned below is already scattered around test contracts.

• CEP18
• CEP78
• Ownable (single-user ownership)
• AccessControl (many user ownership with roles)
• Escrow (keep a balance per entity with entrypoints fn deposit and fn withdraw)

[devendran-m]

Superseded by Jira ticket CORE-13