Add common dependencies

[ErikSchierboom]

This PR pre-loads the following dependencies:

• QuickCheck
• lens
• parallel
• vector
• split
• random
• string-conversions

See https://github.com/exercism/haskell/issues/1006

[ErikSchierboom]

@petertseng Does this look okay to you?

[ErikSchierboom]

I'm wondering, would it be a good idea or a bad idea to add a comment explaining, for each dependency, why it's in this list? Right now I don't yet see a reason to do that. Perhaps that idea will become useful when this list of dependencies is audited later on and the maintainers of the test runner have to decide whether to keep or dump a given dependency, but since this list is just starting nobody is sure when that will happen. But let us remember that idea for later.

I agree. In the future, it is probably best to have a separate document listing all the dependencies, as then the test runner code itself could parse any errors and remarkt that the student can only use one of the supported dependencies.

[ErikSchierboom]

@petertseng I've just run the tests on my dnd-character solution (which uses QuickCheck), and it worked!