imp: add extra validation to ica msgs (backport #8734)

[mergify]

Description

closes: #XXXX

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Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Linked to GitHub issue with discussion and accepted design, OR link to spec that describes this work.
• Include changelog entry when appropriate (e.g. chores should be omitted from changelog).
• Wrote unit and integration tests if relevant.
• Updated documentation (docs/) if anything is changed.
• Added godoc comments if relevant.
• Self-reviewed Files changed in the GitHub PR explorer.
• Provide a conventional commit message to follow the repository standards.

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This is an automatic backport of pull request #8734 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 7574333 has failed:

On branch mergify/bp/release/v8.8.x/pr-8734
Your branch is up to date with 'origin/release/v8.8.x'.

You are currently cherry-picking commit 7574333c.
  (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/27-interchain-accounts/types/codec.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/docs/02-apps/02-interchain-accounts/07-tx-encoding.md
	both modified:   modules/apps/27-interchain-accounts/host/keeper/relay_test.go

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