Not requiring self client and consensus state validations during connection handshake

[Farhad-Shabani]

Summary

There will be a spec change to remove self client and consensus state validation during connection handshake. There is already an opened PR in ibc-go to implement the changes. We should consider implementing these changes in ibc-rs as well.

Proposal

A suggestion is we continue exposing self-client and consensus states validation methods as an optional feature under a feature flag. This approach will allow projects that benefit from or wish to maintain their current implementations to do so without disruption.