x/ibc: client protobuf migration

[fedekunze]

Description

replaces #5704

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[cwgoes]

@fedekunze Are we still blocked on upstream Tendermint work here?

[fedekunze]

yeah I need to rebase this to @marbar3778 PR #6471

[colin-axner]

I think this branch is too far gone in terms of conflicts, it'd be much faster to just branch off master and copy paste the proto files over. @fedekunze when tm gets updated in master, want to open a fresh branch we can work off of?

[colin-axner]

closing since there is no need for this branch anymore outside of being a reference