Add compound UID valdiator

src/Appwrite/Utopia/Database/Validator/CompoundUID.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace Appwrite\Utopia\Database\Validator;
+
+use Utopia\Database\Validator\UID;
+use Utopia\Validator;
+
+class CompoundUID extends Validator
+{
+    public function getDescription(): string
+    {
+        return 'Must consist of multiple UIDs separated by a colon. Each UID must contain at most 36 chars. Valid chars are a-z, A-Z, 0-9, and underscore. Can\'t start with a special char.';
+    }
+
+    public function isArray(): bool
+    {
+        return false;
+    }
+
+    public function isValid($value): bool
+    {
+        if (!\is_string($value)) {
+            return false;
+        }
+
+        $ids = static::parse($value);
+
+        if (\count($ids) < 2) {
+            return false;
+        }
+
+        foreach ($ids as $id) {
+            $validator = new UID();
+            if (!$validator->isValid($id)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public function getType(): string
+    {
+        return self::TYPE_STRING;
+    }
+
+    public static function parse(string $key): array
+    {
+        $parts = \explode(':', $key);
+        $result = [];
+
+        foreach ($parts as $part) {
+            $result[] = $part;
+        }
+
+        return $result;
+    }
+}