Fix various issues in Dijkstra CddlSpec to make all the tests pass

[Soupstraw]

Description

This PR fixes various issues in Dijkstra's CddlSpec to make the tests pass. The PR is intended to be reviewed commit-by-commit.

Checklist

• Commits in meaningful sequence and with useful messages.
• Tests added or updated when needed.
• CHANGELOG.md files updated for packages with externally visible changes.
  NOTE: New section is never added with the code changes. (See RELEASING.md).
• Versions updated in .cabal and CHANGELOG.md files when necessary, according to the
  versioning process.
• Version bounds in .cabal files updated when necessary.
  NOTE: If bounds change in a cabal file, that package itself must have a version increase. (See RELEASING.md).
• Code formatted (use scripts/fourmolize.sh).
• Cabal files formatted (use scripts/cabal-format.sh).
• CDDL files are up to date (use scripts/gen-cddl.sh)
• hie.yaml updated (use scripts/gen-hie.sh).
• Self-reviewed the diff.

[lehins]

(As discussed on a call) Term has an Ord instance, so the natural questions comes to mind:

• why do we need to pass custom eq function as an argument, which is always set to (==)?
• Why do we use O(n^2) complexity function nubOrd, when we could just use the Ord and stick those in a Set?

Suggested change

	forall name a.
	(KnownSymbol name, IsType0 a) => Proxy name -> Int -> (Term -> Term -> Bool) -> a -> GRuleCall
	mkMaybeTaggedSet pname n eq = binding $ \x ->
	forall name a.
	(KnownSymbol name, IsType0 a) => Proxy name -> Int -> a -> GRuleCall
	mkMaybeTaggedSet pname n = binding $ \x ->