Polkadot companion #6603: Use a `BoundedVec` in `ValidationResult` (#2161)

* Convert message `Vec`s into `BoundedVec`s

* cargo fmt

* Fix missing conversions in collator

* Fix the fix

* Fix the fix to the fix

* Fix tests

* Fix^4

* Avoid use of unwrap

* update lockfile for {"substrate", "polkadot"}

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Co-authored-by: parity-processbot <>