FIR: don't check annotations on returnTypeRefs that are not of real kind

This fixes an exception in FirAnnotationChecker where we tried to report
repeated annotations on implicit type refs that have no source.

compiler/fir/analysis-tests/testData/resolveWithStdlib/repeatedAnnotations.kt

@@ -0,0 +1,37 @@
+// FILE: Some.java
+import java.util.List;
+
+public class Some {
+    public static List<@SomeAnn(1) @SomeAnn(2) String> foo() {
+        return null;
+    }
+}
+
+// FILE: SomeAnn.java
+
+@Target({ElementType.TYPE_PARAMETER, ElementType.TYPE_USE})
+public @interface SomeAnn {
+    int value();
+}
+
+
+// FILE: test.kt
+fun <T> foo(bar: () -> T) {
+
+}
+
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+fun baz(): @Ann <!REPEATED_ANNOTATION!>@Ann<!> String = "12"
+fun qux() = Some.foo()[0]
+
+fun test() {
+    foo({ Some.foo()[0] })
+    foo({ baz() })
+    foo({ qux() })
+    foo(fun(): @Ann <!REPEATED_ANNOTATION!>@Ann<!> String {
+        return ""
+    })
+}
+