Avoid closure allocation in safeFilter / implodeFiltered

Pass a static array callable to array_filter instead of allocating a
fresh closure on every call. Required promoting safeFilterFunc from
protected to public so array_filter (external scope) can resolve it.

Measured on cloudinary_php URL workload (12-run alternating A/B,
5000 iterations each):
  (string) new Image()  -8.2%   (26.67 -> 24.49 us/op)
  $image->toUrl()       -15.5%  (23.08 -> 19.50 us/op)

Author: const-cloudinary

src/Utils/ArrayUtils.php

@@ -133,8 +133,6 @@ public static function implodeFiltered(
         callable|null $filterCallback = null,
         int $flag = 0
     ): string {
-        $filterCallback ??= fn($value) => ArrayUtils::safeFilterFunc($value);
-
         return self::safeImplode($glue, self::safeFilter($pieces, $filterCallback, $flag));
     }
 
@@ -188,7 +186,7 @@ public static function escapedImplode(string|array $glue, array|null $pieces): s
      * @see strlen
      * @see empty
      */
-    protected static function safeFilterFunc(mixed $value): bool|int
+    public static function safeFilterFunc(mixed $value): bool|int
     {
         if ($value === null) {
             return 0;
@@ -224,9 +222,11 @@ public static function safeFilter(
         callable|null $callback = null,
         int $flag = 0
     ): ?array {
-        $callback ??= fn($value) => ArrayUtils::safeFilterFunc($value);
+        if ($input === null) {
+            return null;
+        }
 
-        return is_null($input) ? $input : array_filter($input, $callback, $flag);
+        return array_filter($input, $callback ?? [self::class, 'safeFilterFunc'], $flag);
     }
 
     /**