LibJS: Implement void operator

Author: https://github.com/linusg
Commit: d30db07048
Pull-request: https://github.com/SerenityOS/serenity/pull/1811

Libraries/LibJS/Tests/void-basic.js

@@ -0,0 +1,20 @@
+load("test-common.js");
+
+try {
+    assert(void "" === undefined);
+    assert(void "foo" === undefined);
+    assert(void 1 === undefined);
+    assert(void 42 === undefined);
+    assert(void true === undefined);
+    assert(void false === undefined);
+    assert(void null === undefined);
+    assert(void undefined === undefined);
+    assert(void function () {} === undefined);
+    assert(void (() => {}) === undefined);
+    assert(void (() => "hello friends")() === undefined);
+    assert((() => void "hello friends")() === undefined);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}