JVM_IR: use nullability when boxing/unboxing inline class types

Given inline class V(Any?), a coercion from (Object, V) to (Object, V?)
is boxing.

In theory, the same issue in the old backend can be fixed by making
`KotlinTypeMapper.mapUnderlyingTypeOfInlineClassType` use
`computeExpandedTypeForInlineClass`, but for some reason this breaks a
lot of stuff.

 #KT-48430 Fixed

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java

@@ -13176,6 +13176,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/inlineClasses/boxImplDoesNotExecuteInitBlock.kt");
         }
 
+        @TestMetadata("boxNullableForFakeOverride.kt")
+        public void testBoxNullableForFakeOverride() throws Exception {
+            runTest("compiler/testData/codegen/box/inlineClasses/boxNullableForFakeOverride.kt");
+        }
+
         @TestMetadata("boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt")
         public void testBoxNullableValueOfInlineClassWithNonNullUnderlyingType() throws Exception {
             runTest("compiler/testData/codegen/box/inlineClasses/boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -12582,6 +12582,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/inlineClasses/boxImplDoesNotExecuteInitBlock.kt");
         }
 
+        @TestMetadata("boxNullableForFakeOverride.kt")
+        public void testBoxNullableForFakeOverride() throws Exception {
+            runTest("compiler/testData/codegen/box/inlineClasses/boxNullableForFakeOverride.kt");
+        }
+
         @TestMetadata("boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt")
         public void testBoxNullableValueOfInlineClassWithNonNullUnderlyingType() throws Exception {
             runTest("compiler/testData/codegen/box/inlineClasses/boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -12647,6 +12647,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/inlineClasses/boxImplDoesNotExecuteInitBlock.kt");
         }
 
+        @TestMetadata("boxNullableForFakeOverride.kt")
+        public void testBoxNullableForFakeOverride() throws Exception {
+            runTest("compiler/testData/codegen/box/inlineClasses/boxNullableForFakeOverride.kt");
+        }
+
         @TestMetadata("boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt")
         public void testBoxNullableValueOfInlineClassWithNonNullUnderlyingType() throws Exception {
             runTest("compiler/testData/codegen/box/inlineClasses/boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java

@@ -6727,6 +6727,11 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/inlineClasses/boxImplDoesNotExecuteInitBlock.kt");
         }
 
+        @TestMetadata("boxNullableForFakeOverride.kt")
+        public void testBoxNullableForFakeOverride() throws Exception {
+            runTest("compiler/testData/codegen/box/inlineClasses/boxNullableForFakeOverride.kt");
+        }
+
         @TestMetadata("boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt")
         public void testBoxNullableValueOfInlineClassWithNonNullUnderlyingType() throws Exception {
             runTest("compiler/testData/codegen/box/inlineClasses/boxNullableValueOfInlineClassWithNonNullUnderlyingType.kt");