Minor. Add tests checking not-null assertions

More precisely these tests check cases when expected type
was somehow obtained from captured type (in member scope with projections)

compiler/testData/codegen/notNullAssertions/assertionForNotNullCaptured.kt

@@ -0,0 +1,7 @@
+class A<T> {
+    fun add(element: T) {}
+}
+
+public fun <R : Any> foo(x: MutableCollection<in R>, block: java.util.AbstractList<R>) {
+    x.add(block.get(0))
+}