Kapt: Do not use awkward ('$' -> '/') logic for KAPT3 class builder mode

So (for the most often reproduction case) #KT-19433 Fixed

Before this commit, internal names for nested classes were written as test/Foo/Bar (comparing to test/Foo$Bar in the normal mode), as getting qualified names from such internal names was trivial. But, because of IC, we needed to write class files to the disk, so our decompiler could find such "broken" classes and read it in a wrong way.

plugins/kapt3/testData/converter/nestedClassesNonRootPackage.kt

@@ -0,0 +1,84 @@
+// FILE: test/JavaClass.java
+package test;
+
+class JavaClass {
+    class Foo {
+        class Bar {}
+    }
+}
+
+//FILE: test/J$B.java
+package test;
+
+public class J$B {
+    public class C {}
+
+    public class D$E {
+        class F {}
+        class F$G {}
+    }
+
+    public class D$$E {}
+    public class D$$$E {}
+}
+
+// FILE: a.kt
+package test
+
+interface IFoo {
+    interface IBar {
+        annotation class Anno(vararg val value: kotlin.reflect.KClass<*>)
+
+        @Anno(IZoo::class)
+        interface IZoo
+    }
+}
+
+class Experiment {
+    annotation class Type
+
+    @Type
+    data class Group(s: String)
+}
+
+class Foo {
+    open class Bar {
+        object Zoo
+    }
+}
+
+class `A$B` {
+    class C
+
+    @JvmField lateinit var c: C
+    @JvmField lateinit var de: `D$E`
+
+    @JvmField lateinit var jc: `J$B`.C
+    @JvmField lateinit var jde: `J$B`.`D$E`
+
+    class `D$E` {
+        class F
+        class `F$G`
+
+        @JvmField lateinit var f: F
+        @JvmField lateinit var fg: `F$G`
+
+        @JvmField lateinit var jf: `J$B`.`D$E`.F
+        @JvmField lateinit var jfg: `J$B`.`D$E`.`F$G`
+    }
+
+    class `D$$E`
+    class `D$$$E`
+
+    @JvmField lateinit var dee: `D$$E`
+    @JvmField lateinit var deee: `D$$$E`
+
+    @JvmField lateinit var jdee: `J$B`.`D$$E`
+    @JvmField lateinit var jdeee: `J$B`.`D$$$E`
+}
+
+@IFoo.IBar.Anno(IFoo.IBar.IZoo::class, Foo.Bar::class)
+class Test1(val zoo: Foo.Bar.Zoo) : Foo.Bar(), IFoo.IBar, IFoo.IBar.IZoo {
+    fun a(): Thread.State = Thread.State.NEW
+    fun b(foo: JavaClass.Foo, bar: JavaClass.Foo.Bar) {}
+}