Implement ICS09 loopback (localhost) client

[fedekunze]

Summary

Implement ICS09 client within x/ibc/09-localhost and integrate with ICS02's clientType switch statements.

NOTE: rebase on top of #5485 or wait until it's merged to ibc-alpha. Does not block GoZ

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[cwgoes]

💯 - just to note, this is not critical and does not block 1.0.

[gregdhill]

I would be happy to tackle this issue if it's still available, @cwgoes @fedekunze?

[cwgoes]

I would be happy to tackle this issue if it's still available, @cwgoes @fedekunze?

Absolutely, please do!