Fix account contract_names duplicates

[janezpodhostnik]

Problem Definition

Data inconsistency in some "contracts" registers.

This was reported in cadence onflow/cadence#2252

Some Accounts have duplicated contract names in the contract_names register. This should not be the case.

A scan of the network showed that there are only 2 accounts on mainnet and only a few on testnet that have this problem.

mainnet:

address=f233dcee88fe0abe contract_names=["FungibleToken","FungibleToken","FungibleTokenMetadataViews","FungibleTokenSwitchboard"]
 address=1d7e57aa55817448 contract_names=["MetadataViews","NonFungibleToken","NonFungibleToken"]

Everything points to this being introduced with the initial migration to multiple contracts per account, or by a very old bug.

Proposed Solution

Create a storage migration to fix accounts with this inconsistency.

Definition of Done

For all accounts the contract_names register should not contain duplicates.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.