FIR checker: check if callable reference targets are allowed members

compiler/fir/analysis-tests/testData/resolve/references/referenceToExtension.kt

@@ -36,8 +36,8 @@ class NoGenericTest {
     fun B.extensionFun(): A = A()
 
     fun test_1() {
-        val extensionValRef = B::extensionVal
-        val extensionFunRef = B::extensionFun
+        val extensionValRef = <!EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>B::extensionVal<!>
+        val extensionFunRef = <!EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>B::extensionFun<!>
     }
 
     fun test_2() {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -2968,6 +2968,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/diagnostics/tests/callableReference/property"), Pattern.compile("^(.+)\\.kt$"), Pattern.compile("^(.+)\\.fir\\.kts?$"), true);
                 }
 
+                @Test
+                @TestMetadata("backingField.kt")
+                public void testBackingField() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/callableReference/property/backingField.kt");
+                }
+
                 @Test
                 @TestMetadata("classFromClass.kt")
                 public void testClassFromClass() throws Exception {