Fix DeserializerForDecompiler: create package fragment provider for missing dependencies

idea/testData/libraries/decompiledText/DependencyOnNestedClasses/DependencyOnNestedClasses.kt

@@ -0,0 +1,9 @@
+package test
+
+import dependency.*
+
+public class DependencyOnNestedClasses : D.Nested() {
+    fun f(nc: D.NestedInClassObject, i: D.Inner, ii: D.Inner.Inner, nn: D.Nested.Nested): D.Nested {
+        return D.Nested()
+    }
+}