Introduce a separate StackValue class for lateinit local vars

Local lateinit var differs in behavior from a simple local var,
and logic that relies of 'instanceof Local' checks assuming that all
instances of Local are simple local vars can produce faulty code
(as in KT-23260, where a local lateinit var was not explicitly put on
stack when passed as an argument to an inline function, thus causing
null propagation).

 #KT-23260 Fixed Target versions 1.2.50

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -13812,6 +13812,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                     runTest("compiler/testData/codegen/box/properties/lateinit/local/capturedLocalLateinit.kt");
                 }
 
+                @TestMetadata("kt23260.kt")
+                public void testKt23260() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/properties/lateinit/local/kt23260.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("localLateinit.kt")
                 public void testLocalLateinit() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/local/localLateinit.kt");