Align generic signature for inner classes to work as in Java

#KT-10397 Fixed

According to JVMS (p. 4.3.4) inner classes should be separated with `$` in generic signature.

Note that in Java, inner types separated with `.` after first parameterized type, and now we preserve the same behaviour. See tests for clarification.

compiler/testData/writeSignature/GenericInnerClassWithSimpleOuter.kt

@@ -0,0 +1,9 @@
+class Outer {
+    inner class Inner<G>
+
+    fun <A> foo(): Inner<A> = TODO()
+}
+
+// method: Outer::foo
+// jvm signature: ()LOuter$Inner;
+// generic signature: <A:Ljava/lang/Object;>()LOuter$Inner<TA;>;