Add diamond beacon proxy implementation

[ItsNickBarry]

The diamond beacon proxy pattern that we've been using and recommending is not minimal, and includes some features that are non-functional in the context of proxies which reference the beacon. A proper beacon should include DiamondReadable and DiamondWritable, but not DiamondBase. A SolidStateDiamond should not be used as a beacon because it includes DiamondBase and several other extensions.