[FIR] fix subtyping for definitely notnull types.

The current implementation doesn't consider Foo a subtype of Captured<in
Foo>!!, since AbstractTypeCheckerContext::checkSubtypeForSpecialCases
does not handle DefinitelyNotNullType cases. This PR adds handling of
DefinitelyNotNullType by looking at its original type.

^KT-42824 Fixed

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

@@ -17441,6 +17441,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/javaInterop/generics/javaNestedSamInterface.kt");
             }
 
+            @TestMetadata("kt42824.kt")
+            public void testKt42824() throws Exception {
+                runTest("compiler/testData/codegen/box/javaInterop/generics/kt42824.kt");
+            }
+
             @TestMetadata("kt42825.kt")
             public void testKt42825() throws Exception {
                 runTest("compiler/testData/codegen/box/javaInterop/generics/kt42825.kt");