Ethereum light client improvements (#677)

* Use proper enums when providing the trusted sync committee in updates,
instead of C-like `is_next` logic: #648
* Implements `update_state_on_misbehaviour` on the ethereum light
client: #675
* Uses the block timestamp that is provided by the native chain instead
of the relayer during the ethereum light client updates. #676
* Removes the `ibc-rs` dependency from the release builds, it will only
be there as a dev dependency.
* Introduces more relevant names for proofs that are used to update the
storage root.