Fix occasional reflection test failure

The cache in moduleByClassLoader.kt contains weak references to instances of
RuntimeModuleData. However, prior to this change no one else had any _strong_
reference to the corresponding RuntimeModuleData: KClassImpl depends on the
ModuleDescriptor almost directly. Therefore the weak references were sometimes
garbage collected and a new module was constructed for a new reflection object,
which resulted in broken equality between two reflection objects.

No test added because it was rather hard to come up with (and, more
importantly, to support) a test case.

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KCallableContainerImpl.kt

@@ -33,6 +33,11 @@ import java.lang.reflect.Method
 import kotlin.reflect.KotlinReflectionInternalError
 
 abstract class KCallableContainerImpl {
+    // Note: this is stored here on a soft reference to prevent GC from destroying the weak reference to it in the moduleByClassLoader cache
+    val moduleData by ReflectProperties.lazySoft {
+        jClass.getOrCreateModule()
+    }
+
     abstract val jClass: Class<*>
 
     abstract val scope: JetScope

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt

@@ -28,7 +28,6 @@ class KClassImpl<T>(override val jClass: Class<T>) : KCallableContainerImpl(), K
     // resulting in infinite recursion
 
     val descriptor by ReflectProperties.lazySoft {
-        val moduleData = jClass.getOrCreateModule()
         val classId = classId
 
         val descriptor =