Implementation and tests for KT-5840 and newly created KT-7204. Now a safe call provides not-null receiver state *inside* argument list. It works also for ?. chains. #KT-5840 Fixed.

On the other hand, argument states do not propagate to successor statements for a safe call. #KT-7204 Fixed. A few additional comments.

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

@@ -0,0 +1,8 @@
+fun foo(y: Int): Int {
+    return y + 1
+}
+
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    return foo(x?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size() - 1)!!.length())
+}