feat: adding 09-localhost loopback client module (backport #3229)

[mergify]

This is an automatic backport of pull request #3229 done by Mergify.
Cherry-pick of d840c69 has failed:

On branch mergify/bp/release/v7.1.x/pr-3229
Your branch is up to date with 'origin/release/v7.1.x'.

You are currently cherry-picking commit d840c699.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   docs/.vuepress/config.js
	new file:   docs/ibc/light-clients/localhost/client-state.md
	new file:   docs/ibc/light-clients/localhost/connection.md
	new file:   docs/ibc/light-clients/localhost/integration.md
	new file:   docs/ibc/light-clients/localhost/overview.md
	new file:   docs/ibc/light-clients/localhost/state-verification.md
	modified:   docs/ibc/params.md
	new file:   docs/ibc/troubleshooting.md
	new file:   docs/migrations/v7-to-v7_1.md
	new file:   e2e/tests/interchain_accounts/localhost_test.go
	new file:   e2e/tests/transfer/localhost_test.go
	new file:   e2e/testsuite/events.go
	modified:   modules/core/02-client/abci.go
	modified:   modules/core/02-client/genesis.go
	modified:   modules/core/02-client/keeper/client_test.go
	modified:   modules/core/02-client/keeper/grpc_query.go
	modified:   modules/core/02-client/keeper/grpc_query_test.go
	modified:   modules/core/02-client/keeper/keeper.go
	modified:   modules/core/02-client/keeper/keeper_test.go
	modified:   modules/core/02-client/keeper/migrations.go
	modified:   modules/core/02-client/migrations/v7/expected_keepers.go
	new file:   modules/core/02-client/migrations/v7/localhost.go
	new file:   modules/core/02-client/migrations/v7/localhost_test.go
	modified:   modules/core/02-client/types/client.pb.go
	modified:   modules/core/02-client/types/keys.go
	modified:   modules/core/02-client/types/params.go
	modified:   modules/core/03-connection/genesis.go
	modified:   modules/core/03-connection/keeper/grpc_query_test.go
	modified:   modules/core/03-connection/keeper/handshake.go
	modified:   modules/core/03-connection/keeper/handshake_test.go
	modified:   modules/core/03-connection/keeper/keeper.go
	modified:   modules/core/03-connection/keeper/keeper_test.go
	new file:   modules/core/03-connection/keeper/migrations.go
	new file:   modules/core/03-connection/migrations/v7/expected_keepers.go
	new file:   modules/core/03-connection/migrations/v7/localhost.go
	modified:   modules/core/03-connection/types/expected_keepers.go
	modified:   modules/core/03-connection/types/msgs.go
	modified:   modules/core/04-channel/keeper/events.go
	modified:   modules/core/04-channel/keeper/handshake.go
	modified:   modules/core/04-channel/keeper/handshake_test.go
	modified:   modules/core/04-channel/types/expected_keepers.go
	modified:   modules/core/04-channel/types/msgs_test.go
	modified:   modules/core/exported/client.go
	modified:   modules/core/exported/connection.go
	modified:   modules/core/module.go
	modified:   modules/core/types/codec.go
	modified:   modules/light-clients/07-tendermint/client_state_test.go
	new file:   modules/light-clients/09-localhost/client_state.go
	new file:   modules/light-clients/09-localhost/client_state_test.go
	new file:   modules/light-clients/09-localhost/codec.go
	new file:   modules/light-clients/09-localhost/keys.go
	new file:   modules/light-clients/09-localhost/localhost.pb.go
	new file:   modules/light-clients/09-localhost/localhost_test.go
	modified:   proto/ibc/core/client/v1/client.proto
	new file:   proto/ibc/lightclients/localhost/v2/localhost.proto
	modified:   testing/simapp/app.go
	modified:   testing/simapp/upgrades/upgrades.go
	deleted:    testing/simapp/upgrades/v6/upgrades.go
	deleted:    testing/simapp/upgrades/v7/upgrades.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   .github/workflows/e2e-upgrade.yaml
	both modified:   docs/ibc/events.md
	deleted by us:   e2e/relayer/relayer.go
	deleted by us:   e2e/testconfig/testconfig.go
	deleted by us:   e2e/tests/upgrades/upgrade_test.go
	deleted by us:   e2e/testsuite/codec.go
	deleted by us:   e2e/testsuite/grpc_query.go
	deleted by us:   e2e/testsuite/testsuite.go
	both modified:   modules/core/02-client/keeper/client.go
	both modified:   modules/core/02-client/keeper/proposal.go
	both modified:   modules/core/02-client/types/errors.go
	both modified:   modules/core/03-connection/keeper/verify.go
	both modified:   modules/core/03-connection/types/msgs_test.go
	both modified:   modules/core/04-channel/keeper/packet.go
	both modified:   modules/core/04-channel/types/msgs.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[colin-axner]

the .gitignore didn't work? Maybe we could add a github action to auto remove the e2e directory

[chatton]

not a bad idea

[damiannolan]

I've fixed up the conflicts, leaving my approval on this PR.

• Removed /e2e directory
• Removed e2e-upgrade.yaml
• Fixed all occurrences of errorsmod -> sdkerrors

[damiannolan]

I missed one last one which was the localhost client state file using ibcerrors instead of sdkerrors.

Should be g2g now

[chatton]

LGTM!

[colin-axner]

Thanks @damiannolan ❤️