chore: Add consensus state heights query (backport #1336)

[mergify]

This is an automatic backport of pull request #1336 done by Mergify.
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Changes to be committed:
	modified:   docs/ibc/proto-docs.md
	modified:   modules/core/02-client/client/cli/cli.go
	modified:   modules/core/02-client/client/cli/query.go
	modified:   modules/core/02-client/keeper/grpc_query.go
	modified:   modules/core/02-client/types/query.pb.gw.go
	modified:   modules/core/keeper/grpc_query.go
	modified:   proto/ibc/core/client/v1/query.proto

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md
	both modified:   docs/client/swagger-ui/swagger.yaml
	both modified:   modules/core/02-client/keeper/grpc_query_test.go
	both modified:   modules/core/02-client/types/query.pb.go

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[crodriguezvega]

The original PR had the route "/ibc/core/client/v1/consensus_states/heights/{client_id}", but I just realized that it would be more consistent with heights at the end, so I changed it here. It's a bit sneaky, but I hope it's ok. I will also open a PR to main to update the route.