Update and reorganize conformance tests

[Soupstraw]

Description

This PR does some reorganizing of the V2 constrained generators and conformance tests.

• Conway era V2 specs are moved from cardano-ledger-test to cardano-ledger-conway:testlib
• Made a ExecutableSpecRule typeclass interface to have a common interface for running conformance tests for each rule

This only touches the infrastructure for running conformance tests with V2 constrained generators. The tests themselves will be added in a follow-up PR.

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]

There is a missing TypeOperators build failure for newer GHCs. Other than that the PR is ready to be merged