Add more tests

typechecker/src/Initial.hs

typechecker/src/Tc/Gen/Expr.hs

typechecker/src/Tc/Gen/Subst.hs

typechecker/src/Tc/Solver/Equality.hs

typechecker/src/Tc/Solver/Monad.hs

typechecker/src/Type.hs

typechecker/test/cases/should-typecheck/apply-infer.hs

typechecker/test/cases/should-typecheck/apply-infer.output

typechecker/test/cases/should-typecheck/until-infer.hs

typechecker/test/cases/should-typecheck/until-infer.output

typechecker/test/cases/should-typecheck/untilTwo-infer.hs

...checker/test/cases/should-typecheck/untilTwo-infer.output