Fail PParamsUpdate deserialization for invalid costmodels in Conway

[teodanciu]

Description

Closes #3772

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated
• When applicable, versions are updated in .cabal and CHANGELOG.md files according to the
  versioning process.
• The version bounds in .cabal files for all affected packages are updated. If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• All visible changes are prepended to the latest section of a CHANGELOG.md for the affected packages. New section is never added with the code changes. (See RELEASING.md)
• Code is formatted with fourmolu (use scripts/fourmolize.sh)
• Cabal files are formatted (use scripts/cabal-format.sh)
• hie.yaml has been updated (use scripts/gen-hie.sh)
• Self-reviewed the diff

[lehins]

Not quite what needed to be done, but close. Test cases are very nice! Thank you for that

[lehins]

You also need to update what sort of CostModel we generate fro PParamUpdates here: https://github.com/input-output-hk/cardano-ledger/blob/3d207b01dca78b231874ab27a2e016cf22753f86/eras/conway/impl/testlib/Test/Cardano/Ledger/Conway/Arbitrary.hs#L507

I suspect that is the reason for CI failures

[lehins]

This is beautiful!

I love the extensive test suite for this functionality!

All of the comments I made are mere suggestions.