feat: make ResultOk available at top level

Author: MilesCranmer

src/DynamicExpressions.jl

@@ -75,7 +75,7 @@ import .StringsModule: get_op_name, get_pretty_op_name
     OperatorEnum, GenericOperatorEnum, @extend_operators, set_default_variable_names!
 @reexport import .EvaluateModule:
     eval_tree_array, differentiable_eval_tree_array, EvalOptions
-import .EvaluateModule: ArrayBuffer
+import .EvaluateModule: ArrayBuffer, ResultOk
 @reexport import .EvaluateDerivativeModule: eval_diff_tree_array, eval_grad_tree_array
 @reexport import .ChainRulesModule: NodeTangent, extract_gradient
 @reexport import .SimplifyModule: combine_operators, simplify_tree!