[JVM IR] ForLoopsLowering: Keep IMPLICIT_NOTNULL type-casts in next()

and `componentN()` calls.

There were issues when we have iterables from Java where the element
type has "not null" type information.

compiler/testData/codegen/box/ranges/javaInterop/javaCollectionOfInheritedNotNull.kt

@@ -0,0 +1,34 @@
+// !LANGUAGE: +StrictJavaNullabilityAssertions
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
+// WITH_RUNTIME
+
+// FILE: box.kt
+import kotlin.test.*
+
+fun box(): String {
+    val actualValues = mutableListOf<Int>()
+    for (i in JImpl().listOfNotNull()) {
+        actualValues += i
+    }
+    assertEquals(listOf(42, -42), actualValues)
+    return "OK"
+}
+
+interface J {
+    fun listOfNotNull(): List<Int>
+}
+
+// FILE: JImpl.java
+import java.util.*;
+
+public class JImpl implements J {
+    // Type argument (Int) gets @EnhancedNullability because it is not nullable in overridden Kotlin function.
+    @Override
+    public List<Integer> listOfNotNull() {
+        List<Integer> list = new ArrayList<>();
+        list.add(42);
+        list.add(-42);
+        return list;
+    }
+}