e2e: add v6 -> v7 e2e upgrade tests

[colin-axner]

Summary

Add an e2e test which tests the upgrade from a v6 to v7 chain.

Pre-upgrade logic

• Create multiple tendermint clients, ideally update both at least once
• Create a channel, send a transfer and receive a transfer
• Create a solo machine client (no need to perform actions with the solo machine client)

Post upgrade logic

• Send a packet on the existing channel
• Query the tendermint clients
• Query the solo machine client
• Optional: send a MsgUpdate in reference to the solo machine client (proof can be invalid, mostly want to ensure the msg does not panic when referencing a solo machine clientID)

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned