KT-2960 Perform control flow checks for package property initializers

#KT-2960 fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2960.kt

@@ -0,0 +1,27 @@
+//KT-2960 Perform control flow checks for package property initializers
+
+package b
+
+class P {
+    var x : Int = 0
+        private set
+}
+
+val p = P()
+var f = { -> <!INVISIBLE_SETTER!>p.x<!> = 32 }
+
+val o = object {
+    fun run() {
+        <!INVISIBLE_SETTER!>p.x<!> = 4
+
+        val z : Int
+        doSmth(<!UNINITIALIZED_VARIABLE, UNINITIALIZED_VARIABLE!>z<!>)
+    }
+}
+
+val g = { ->
+    val x: Int
+    doSmth(<!UNINITIALIZED_VARIABLE!>x<!>)
+}
+
+fun doSmth(i: Int) = i