ESQL: Add url_decode function (elastic#133494)

Author: mouhc1ne

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/AbstractUrlEncodeDecodeTestCase.java

@@ -15,6 +15,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Supplier;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -88,11 +89,11 @@ public static TestCaseSupplier.TestCase createTestCaseWithRandomString(
 
     private static RandomUrl generateRandomUrl() {
         String protocol = randomFrom("http://", "https://", "");
-        String domain = String.format("%s.com", randomAlphaOfLengthBetween(3, 10));
+        String domain = String.format(Locale.ROOT, "%s.com", randomAlphaOfLengthBetween(3, 10));
         String path = randomFrom("", "/" + randomAlphanumericOfLength(5) + "/");
         String query = randomFrom("", "?" + randomAlphaOfLength(5) + "=" + randomAlphanumericOfLength(5));
 
-        String plain = String.format("%s%s%s%s", protocol, domain, path, query);
+        String plain = String.format(Locale.ROOT, "%s%s%s%s", protocol, domain, path, query);
         String encoded = encode(plain);
 
         return new RandomUrl(plain, encoded);