By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Drop unused QuickCheck + genvalidity-sydtest-aeson deps; rename shadowing
CI flagged two issues:
- nix-build's -Werror=name-shadowing tripped on 'name' and 'str'
locals shadowing OptEnvConf re-exports. Rename to 'pname' and 'input'.
- nix-build's -Werror=unused-packages tripped on QuickCheck (the only
user was the Gen module's listOf+suchThat string generator, which
went away with the JSON config) and genvalidity-sydtest-aeson (its
sole user was the deleted jsonSpec on MutationDriverConfig).