Check for storage collisions in metadata
Created by: HCastano
As a follow up to https://github.com/paritytech/ink/pull/1217 we'll want cargo-contract
to go through the contract's metadata and determine whether or not any storage collisions
arise. While the probably of this is quite low, the impact of a storage collision would
be problematic for anyone interacting with the smart contract.
See this comment for more context: https://github.com/paritytech/ink/issues/1134#issuecomment-1062948188