Implement ability to validate client substitute when recovering a client

[seanchen1991]

Problem Statement

As part of implementing ADR-026 in ibc-rs, a frozen/expired client is recovered by updating it to match a substitute client.

Before the actual client recovery process can proceed, the substitute client must be validated to ensure that it:

1. is the same type as the subject client
2. matches all of the same parameters as the subject client, i.e., that the frozen height, latest height, and chain ID all match

Proposal

A new method check_substitute is added to the ClientStateValidation trait.