Unwrap Kotlin inline value classes return values

The result returned by Kotlin reflective invocation of a function
returning an inline value class is wrapped, which makes sense
from Kotlin POV but from a JVM perspective the associated value
and type should be unwrapped to be consistent with what
would happen with a reflective invocation done by Java.

This commit unwraps such result.

Closes gh-33026

spring-web/src/test/kotlin/org/springframework/web/method/support/InvocableHandlerMethodKotlinTests.kt

@@ -104,6 +104,12 @@ class InvocableHandlerMethodKotlinTests {
 		Assertions.assertThat(value).isEqualTo(1L)
 	}
 
+	@Test
+	fun valueClassReturnValue() {
+		val value = getInvocable(ValueClassHandler::valueClassReturnValue.javaMethod!!).invokeForRequest(request, null)
+		Assertions.assertThat(value).isEqualTo("foo")
+	}
+
 	@Test
 	fun valueClassDefaultValue() {
 		composite.addResolver(StubArgumentResolver(Double::class.java))
@@ -200,6 +206,9 @@ class InvocableHandlerMethodKotlinTests {
 
 	private class ValueClassHandler {
 
+		fun valueClassReturnValue() =
+			StringValueClass("foo")
+
 		fun longValueClass(limit: LongValueClass) =
 			limit.value
 
@@ -246,6 +255,9 @@ class InvocableHandlerMethodKotlinTests {
 
 	data class Animal(override val name: String) : Named
 
+	@JvmInline
+	value class StringValueClass(val value: String)
+
 	@JvmInline
 	value class LongValueClass(val value: Long)