Automatic client upgrades

[adizere]

Crate

Summary

Add support in Hermes to detect a chain upgrade and to automatically trigger the upgrading of all clients which target the upgraded chain.

Problem Definition

The problem is that currently Hermes has only a manual upgrade client command, and we are at a WIP stage on adding a bulk upgrade clients CLI (#763).
It would be good to support client upgrading in a reactive manner; so this feature is an extension to the reactive capabilities (#823) of Hermes, to additionally support client upgrades.

Another problem we'd like to tackle is to extend the end-to-end tests with a scenario for chain & client upgrades.
Currently we only have some manual testing guide for this scenario.

Proposal

• investigate and find which event does a chain generate upon upgrading
  • depends on Emit event upon setting upgrade consensus state cosmos/ibc-go#270
• add mechanism to handle the event, so that Hermes automatically triggers client upgrade
• all clients (which target the upgraded chain) hosted on one of the chains in the config file should be upgraded

Acceptance Criteria

• support for reactive client upgrade
• extension to E2E test suite with appropriate test scenario for chain & client upgrade

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[ljoss17]

Emitting upgrade_chain events should be released with ibc-go v7.0.0 early 2023