Add many new features to the Constrained modues in cardano-ledger-test

[TimSheard]

The goal of this PR was to add Traces of simple transactions, and shrinking to tests generated from constraints.
In order to do this we had to add many new features. Here is a summary

Added module Test.Cardano.Ledger.Constrained.Trace.TraceMonad. A monad for generating traces
Includes an example of making a simple Tx's with 1 input and output.
Added 'actions' that update the Env in the TraceM monad for inputs, outputs and fees.
Added Tests that such Tx's pass the applySTS and that the 'actions' compute the same state.
Added Tests that traces of length 100, are real traces and lead to valid states.
Added Stage.hs, to break up large constraint lists into reusable pieces
Added Two experiments to make Targets invertible.
Added Profile improvements, use HashSet(Name era) rather than Set(Name era)
Parameterized the Preds directory files by UnivSize, so on can control the size of the universes.
Added the Gadt Rule, and sts :: Proof era -> Rule tag -> ...
Replaced Target with RootTarget, added some examples in Vars.hs
Added all the Constrained sub directory tests to the Tests in cardano-ledger-test

Description

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

[MaximilianAlgehed]

@TimSheard it would be great if these two tests from Test.Cardano.Ledger.Constrained.Examples could be included in CI:

  testSpec "Constraint soundness" $ pure $ property prop_soundness
  testSpec "Shrinking soundness" $ pure $ withMaxSuccess 20 $ property prop_shrinking

They are now  -- Tim

[lehins]

Could use a little cleanup, otherwise looks good.