FIR: dump nested classes in loadJava tests

Because those test are single Java files, many of them use a top-level
class as a container for multiple classes to be tested. Such tests do
almost nothing if those nested classes aren't handled.

compiler/testData/loadJava/compiledJava/annotations/CustomAnnotationWithDefaultParameter.fir.txt

@@ -1,2 +1,10 @@
 public abstract interface CustomAnnotationWithDefaultParameter : R|kotlin/Any| {
+    public final annotation class MyAnnotation : R|kotlin/Annotation| {
+        public constructor(first: R|kotlin/String|, second: R|kotlin/String| = String(s)): R|test/CustomAnnotationWithDefaultParameter.MyAnnotation|
+
+    }
+    @R|test/CustomAnnotationWithDefaultParameter.MyAnnotation|(String(f), String(s)) public open class MyTest : R|kotlin/Any| {
+        public constructor(): R|test/CustomAnnotationWithDefaultParameter.MyTest|
+
+    }
 }