[#233] Put testing library code into its own package

Description

Problem

We currently have test-related modules scattered across multiple packages:

• Michelson.Test and Michelson.Doc.Test in morley
• Lorentz.Test in lorentz
• morley-nettest
• Hegdehog generators defined in multiple modules in morley and lorentz

We should move them to one single package, cleveland.

Solution

The overall strategy was this:

1. Since the morley-nettest only contains test-related stuff, we could move everything here, and then
2. Rename this package to cleveland.

However, this would lead to 3 cyclic dependencies at the package-level that had to be resolved first in order to make this strategy feasible. These were discussed in detail here, but here's a summary:

1. There would be a cyclic dependency between morley and cleveland:
   • morley:test:morley-test/bench would depend on cleveland:lib, and cleveland:lib on morley:lib.
   • We solved this by moving morley-test/bench to the cleveland package
2. There would be a cyclic dependency between lorentz and cleveland:
   • lorentz:test:lorentz-test would depend on cleveland:lib, and cleveland:lib on lorentz:lib.
   • We solved this by moving lorentz-test to the cleveland package
3. There would be a cyclic dependency between indigo and cleveland:
   • indigo:test:indigo-test would depend on cleveland:lib (source) and cleveland:test:nettest on indigo:lib (source)
   • We solved this by rewriting the ContractAllocator test to use lorentz instead of indigo.

Outstanding issues

~Because I moved genMText out of Michelson.Text, I also had to export minBoundMChar and maxBoundMChar to make them accessible to Hedgehog.Gen.Michelson. These were previously internal, and I'm personally not very fond of having these in the public interface. I see these possible solutions:

1. Do not reuse min/maxBoundMChar, and simply duplicate them in Hedgehog.Gen.Michelson
2. Replace min/maxBoundMChar with a bounded newtype and accompanying functions, and expose these instead. E.g.:

   newtype MChar = MChar Char
   instance Bounded MChar where ...
   instance Enum MChar where ...
   mkMChar :: Char -> Either String MChar
   mkMTextFromMChars :: [MChar] -> Either String MText

3. Leave min/maxBoundMChar in the public interface, not a big deal.~

Package dependency graph

The package dependency graph now looks like this (excluding morley-prelude and tasty-hunit-compat for simplicity):

(Generated using stack dot --test --bench --prune "morley-prelude,tasty-hunit-compat" | dot -T png -o a.png)

Related issue(s)

Resolves #233 (closed)

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