Store state for IBC lifecycle errors

[nicolaslara]

Background

When running callbacks on the IBC lifecycle (ack or timeout in wasm hooks) we may run into errors (contract doesn't exist, doesn't implement entry point, fails, put of gas, etc). Timeout will return regardless and emit an error, but we should store these and allow querying them.

Suggested Design

• Store any errors in state
• Add a query to retrieve the errors for a packet sequence
• Ensure the state is cleared. Some options are (ii is favored):
  1. Make a new message (and far further, potentially incentives, e.g. gas-token like gas rebate). Let these be pruned after (say) 2 weeks
  2. On every new error, prune 2 oldest errors if they're greater than expiry time (2 weeks)
  3. Run some scheduled code every K blocks

Acceptance Criteria

• all existing and new tests should pass
• there are tests for the failures and new queries