[10.x] Add Conditionable in enum rule

[michaelnabil230]

This PR adds Conditionable trait to Enum rule.

How to use:

Rule::enum(PostStatus::class)
    ->when(
        auth()->user()->is_admin,
        fn ($rule) => $rule->only([PostStatus::APPROVED]),
        fn ($rule) => $rule->only([PostStatus::PADDING]),
    );