New ListWhere Pred added to the Constrained Solver.

[TimSheard]

Added the ListWhere Pred, and a test that it works.
Often we have some record structure, and we would like to generate a list of that structure
But we want each element in that list, to constrain each record field with some constraints.

  [ Sized (ExactSize 10) credsUniv
  , Sized (ExactSize 10) voteUniv
  , ListWhere (Range 2 4) ans (pairT CredR VCredR)
        [ Member (Right (pair1 CredR)) credsUniv, Member (Right (pair2 VCredR)) voteUniv]
  ]

Here we want to constrain 'ans', such that for each pair in 'ans', the first component is a subset of the credsUniv and the second component is a subset of the voteUniv.

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