LibWeb: Implement value argument of URLSearchParams.has

Author: https://github.com/shannonbooth
Commit: 264b5160c2
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1033
Reviewed-by: https://github.com/tcl3 ✅

Tests/LibWeb/Text/input/URL/search-params-has.html

@@ -0,0 +1,11 @@
+<script src="../include.js"></script>
+<script>
+    test(() => {
+        const params = new URLSearchParams('animal=octopus&place=ocean');
+        println(params.has('non-existing-key'));
+        println(params.has('animal'));
+        println(params.has('place', 'non-existing-value'));
+        println(params.has('place', 'ocean'));
+        println(params.has('animal', 'ocean'));
+    });
+</script>