JVM_IR KT-49136 don't optimize null checks on fields and calls

compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt

@@ -0,0 +1,20 @@
+// TARGET_BACKEND: JVM
+// FULL_JDK
+// WITH_REFLECT
+
+class A(val b: B)
+
+class B(val c: String)
+
+fun createByReflection(): A? =
+    A(B("aaa")).apply {
+        val field = javaClass.declaredFields.find { it.name == "b" }!!
+        field.isAccessible = true
+        field.set(this, null)
+    }
+
+fun box(): String {
+    val a = createByReflection()
+    println(a?.b?.c)
+    return "OK"
+}