Feat: Index all files and permissions

[volod-vana]

This PR enhances the Moksha subgraph to provide a complete on-chain view of all registered files and user-granted permissions. These changes are isolated to the Moksha network and do not affect the vana mainnet subgraph.

Key changes:

1. Introduces new File and Permission entities to the shared schema.
2. Adds a new data source to subgraph.moksha.yaml to index events from the DataPermissionImplementation contract.
3. Updates all DataRegistry handlers to index File entities from historical FileAdded events on Moksha.

All changes are additive and backward-compatible. Mainnet configuration remains untouched and will be updated in a future PR when the contracts are deployed there.

Local testing

Query 1: Verify that File entities are being created.

{
  files(first: 5, orderBy: addedAtTimestamp, orderDirection: desc) {
    id
    url
    owner {
      id
    }
    addedAtTimestamp
  }
}

Query 2: Verify that Permission entities are being created.

{
  permissions(first: 5, orderBy: addedAtTimestamp, orderDirection: desc) {
    id
    grant
    user {
      id
    }
    addedAtTimestamp
    nonce
  }
}

[linear]

PRO-394 Index all data registry files and all data permissions in subgraph