imp(channel, connection): add Has function for ConnectionEnd and Channel (backport #3082)

[mergify]

This is an automatic backport of pull request #3082 done by Mergify.
Cherry-pick of b2fb119 has failed:

On branch mergify/bp/release/v6.2.x/pr-3082
Your branch is up to date with 'origin/release/v6.2.x'.

You are currently cherry-picking commit b2fb1192.
  (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:   modules/apps/29-fee/keeper/keeper.go
	modified:   modules/apps/transfer/keeper/keeper.go
	modified:   modules/core/02-client/keeper/keeper.go
	modified:   modules/core/03-connection/keeper/keeper.go
	modified:   modules/core/04-channel/keeper/keeper.go
	modified:   modules/core/04-channel/keeper/keeper_test.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   CHANGELOG.md
	deleted by us:   modules/core/02-client/migrations/v7/store.go
	both modified:   modules/light-clients/07-tendermint/types/store.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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[damiannolan]

👍