Move any_of concept

This avoids an issue with circular includes

include/flux/core/utils.hpp

@@ -69,35 +69,10 @@ template <std::integral To>
 inline constexpr auto checked_cast = detail::checked_cast_fn<To>{};
 
 namespace detail {
-template <bool FirstValue, class First, class... Rest>
-struct disjunction_t { // handle true trait or last trait
-    using type = First;
-};
-
-
-template <class False, class Next, class... Rest>
-struct disjunction_t<false, False, Next,
-    Rest...> { // first trait is false, try the next trait
-    using type = typename disjunction_t<Next::value, Next, Rest...>::type;
-};
-
-template <class... Traits>
-struct disjunction : std::false_type {}; // If _Traits is empty, false_type
-
-template <class First, class... Rest>
-struct disjunction<First, Rest...>
-    : disjunction_t<First::value, First, Rest...>::type {
-    // the first true trait in _Traits, or the last trait if none are true
-};
-
-template <class... Traits>
-inline constexpr bool disjunction_v = disjunction<Traits...>::value;
-
-// VARIABLE TEMPLATE _Is_any_of_v
-template <class T, class... Types>
-inline constexpr bool is_any_of = disjunction_v<std::is_same<T, Types>...>;
-;
+template <typename T, typename... U>
+concept any_of = (std::same_as<T, U> || ...);
 } // namespace detail
+
 } // namespace flux
 
 #endif

include/flux/op/split_string.hpp

@@ -7,16 +7,14 @@
 #define FLUX_STRING_SPLIT_HPP_INCLUDED
 
 #include <flux/op/split.hpp>
+#include <flux/core/utils.hpp>
 
 #include <string_view>
 
 namespace flux {
 
 namespace detail {
 
-template <typename T, typename... U>
-concept any_of = (std::same_as<T, U> || ...);
-
 template <typename C>
 concept character = any_of<C, char, wchar_t, char8_t, char16_t, char32_t>;