Call chains: receiver data flow info is dropped for extensions with nullable receiver #KT-10056 Fixed

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.kt

@@ -0,0 +1,13 @@
+class Foo(val bar: String?)
+
+public inline fun <T, R> T.let(f: (T) -> R): R = f(this)
+
+fun test(foo: Foo?) {
+    foo!!.bar.let {
+        // Correct
+        <!DEBUG_INFO_SMARTCAST!>foo<!>.bar?.length
+        // Unnecessary
+        foo<!UNNECESSARY_SAFE_CALL!>?.<!>bar?.length
+    }
+    <!DEBUG_INFO_SMARTCAST!>foo<!>.bar?.length
+}