engine: resources: Remove named return params

Named return params aren't a favourite feature of mine, and they're
rarely used in the resource writing. They keep popping up because I once
used them and we've been copying and pasting code ever since. Get rid of
them all to help prevent the unnecessary spread.

engine/resources/test.go

@@ -137,7 +137,7 @@ func (obj *TestRes) Watch() error {
 }
 
 // CheckApply method for Test resource. Does nothing, returns happy!
-func (obj *TestRes) CheckApply(apply bool) (checkOK bool, err error) {
+func (obj *TestRes) CheckApply(apply bool) (bool, error) {
 	for key, val := range obj.init.Recv() {
 		obj.init.Logf("CheckApply: Received `%s`, changed: %t", key, val.Changed)
 	}