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

compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt

@@ -0,0 +1,22 @@
+abstract class Z {
+    init {
+        check(this)
+    }
+
+    abstract val b: B
+}
+
+class A(override val b: B) : Z()
+
+class B(val c: String)
+
+fun use(a: Any?) {}
+
+fun check(z: Z) {
+    use(z?.b?.c)
+}
+
+fun box(): String {
+    A(B(""))
+    return "OK"
+}