Introduce KProperty{1,2}.getExtensionDelegate

These two functions are supposed to fix an inconvenience in the design of
KProperty{1,2}.getDelegate for extension properties, where you have to pass an
instance of the extension receiver which is going to be completely ignored

 #KT-8384 Fixed

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -18448,6 +18448,18 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                     throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
                 }
 
+                @TestMetadata("getExtensionDelegate.kt")
+                public void testGetExtensionDelegate() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegate.kt");
+                    try {
+                        doTest(fileName);
+                    }
+                    catch (Throwable ignore) {
+                        return;
+                    }
+                    throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+                }
+
                 @TestMetadata("kPropertyForDelegatedProperty.kt")
                 public void testKPropertyForDelegatedProperty() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/properties/getDelegate/kPropertyForDelegatedProperty.kt");