Develop reusable setups for relayer's integration tests

[Farhad-Shabani]

Context

Now that the full set of IBC layers has been implemented, the relayer's integration tests, specifically those under ics20.rs (e.g. here), involve multiple steps like contract declaration, deployments, handshakes, and client creations, and so on, which are mostly repetitive across tests. Thus it makes sense to develop reusable testing artifacts. We can streamline the setup process, allowing necessary artifacts to be initialized in just a few lines. This approach will make it easier to focus on writing tests.

A similar method has already been applied to Cairo's contract tests, which could serve as a reference.

Caught my eye while reviewing #172.

[rnbguy]

Totally agree. IMO, it's best to implement these as hermes-sdk components.