TransactionCoder.encodeFatContractInstance should only accept normalized values

[paulbrauner-da]

encodeFatContractInstance currently accepts non-normalized values and doesn't check that they are normalized. For instance, it will accept trailing Nones, type annotation, or unsorted maps.

The IDE ledger stores non-normalized (enriched) transactions and then happily translates them using this method in order to produce disclosures. This leads to malformed disclosures as disclosures are expected to be in normal form in 3.x.

We need to at the very least document that this method only accepts normalized values and at best enforce it. We also need to fix the IDE ledger, and potentially other clients that break the precondition. The IDE ledger issue is tracked in #20162.