LibJS: Implement RegExp.prototype [ @@search ]

String.prototype.search is already implemented, but relies on the well-
known Symbol.search, which was not implemented.

Userland/Libraries/LibJS/Tests/builtins/String/String.prototype.search.js

@@ -0,0 +1,47 @@
+test("basic functionality", () => {
+    expect(String.prototype.search).toHaveLength(1);
+
+    expect("hello friends".search("h")).toBe(0);
+    expect("hello friends".search("e")).toBe(1);
+    expect("hello friends".search("l")).toBe(2);
+    expect("hello friends".search("o")).toBe(4);
+    expect("hello friends".search("z")).toBe(-1);
+
+    expect("abc123def".search(/\d/)).toBe(3);
+    expect("abcdef".search(/\d/)).toBe(-1);
+});
+
+test("override exec with function", () => {
+    let calls = 0;
+
+    let re = /test/;
+    let oldExec = re.exec.bind(re);
+    re.exec = function (...args) {
+        ++calls;
+        return oldExec(...args);
+    };
+
+    expect("test".search(re)).toBe(0);
+    expect(calls).toBe(1);
+});
+
+test("override exec with bad function", () => {
+    let calls = 0;
+
+    let re = /test/;
+    re.exec = function (...args) {
+        ++calls;
+        return 4;
+    };
+
+    expect(() => {
+        "test".search(re);
+    }).toThrow(TypeError);
+    expect(calls).toBe(1);
+});
+
+test("override exec with non-function", () => {
+    let re = /test/;
+    re.exec = 3;
+    expect("test".search(re)).toBe(0);
+});