Replace TxProposalProcedures unsafe constructor with an unidirectional pattern

[carbolymer]

Changelog

- description: |
    Replace `TxProposalProcedures` unsafe constructor with an unidirectional pattern. Use `mkTxProposalProcedures` for creating the type instead.
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
   - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
   - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

Previously TxProposalProcedures was not guaranteeing the type consistency: when used, you could insert proposals only to its second argument without inserting it to the first. The logic in cardano-api relies on a fact that the first argument would contain a complete list of proposals, so this would introduce a bug.

This PR replaces TxProposalProcedures constructor with an unidirectional pattern, which does not allow constructing of a type. mkTxProposalProcedures should be used for that.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Jimbo4350]

We should either know or not know if everything was included in substituteExecutionUnits.

[Jimbo4350]

We should change this to:

TxProposalProcedures
    :: Ledger.EraPParams (ShelleyLedgerEra era)
    =>  BuildTxWith build (Map (L.ProposalProcedure (ShelleyLedgerEra era)) (Maybe (ScriptWitness WitCtxStake era)))
    -> TxProposalProcedures build era

Then we can avoid having a separate OSet. Any ProposalProcedure with a corresponding Nothing is key does not require a script witness.

[carbolymer]

But then conversion from ledger tx body to our tx body will result in our datatype having no proposal procedures, because build ~ ViewTx.

Ideally it should be something like (similar to TxCertificates):

TxProposalProcedures
    :: Ledger.EraPParams (ShelleyLedgerEra era)
    => OMap 
         (L.ProposalProcedure (ShelleyLedgerEra era)) 
         (BuildTxWith build (Maybe(ScriptWitness WitCtxStake era)))
    -> TxProposalProcedures build era

But it was rejected on a review, when I was making a first fix to TxProposalProcedures issue with missing proposals.

[Jimbo4350]

Let's go with your counter suggestion 👍

We need to remove BuildTxWith at some point as it's not a useful abstraction.