Add packet forwarding middleware tests

[adizere]

Note: This is a suggestions that came up in a conversation with @soareschen .

Context

The IBC packet forward middleware v1.0.1 was added to the Hub features in the Vega upgrade
https://github.com/cosmos/gaia/blob/main/docs/roadmap/cosmos-hub-roadmap-2.0.md#vega-upgrade-completed-december-14-2021

Problem statement

There are a couple of problems with this:

• There are no integration tests for this feature.
• It is unclear to the members of our team how the feature works.

Furthermore, it seems that the packet forwarding middleware is a potential solution to address some of the scalability problems in Cosmos, suggesting we should develop the expertise around it and understand it more deeply.

Acceptance criteria

• Write an integration test and document the functionality.