Add Conformance.Imp: imptests with conformance

[aniketd]

Description

With a new iteExpectLedgerRuleConformance field added to ImpTestEnv,
we get an overridable function that can be executed within trySubmitTx
for every submitted transaction. To override this hook we have
modifyImpInitExpectLedgerRuleConformance the function. We add a new
Conformance.Imp module to cardano-ledger-conformance package, to
import Conway.Imp and run those tests with a modified "hook" that
runs the LEDGER rule from Agda on the Tx and checkConformance on
the results.

Additions:

• iteExpectLedgerRuleConformance field to ImpTestEnv.
• modifyImpInitExpectLedgerRuleConformance function to override the
  hook.
• Add lenses for all fields of LedgerEnv.

Changes:

• Change trySubmitTx to run the iteExpectLedgerRuleConformance for
  every submitted Tx.

The Problem

We get a failure from the Agda side, telling us that the witsVKeyNeeded utxo txb is not a subset of witsKeyHashes as it should be. We have isolated the issue to be with the translation of spendableInputs, since it is most likely that those aren't being handled in a manner that fits into the problem we are trying to solve with this conformance.

This PR can be merged as it is, since @Soupstraw and I want to work in parallel on related issues.

Closes #4725

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated
• 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)
• 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)
• 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]

@aniketd #4745 was merged yesterday. You can rebase this one on master and finish it up

[Soupstraw]

LGTM

[lehins]

Looks good, but a few minor changes are still needed before we can merge it

[lehins]

Great work. I've made couple suggestions, but neither one is a blocking suggestion, so in order not to block the follow up work I am gonna resolve them and merge the PR.