[Serialization] Migrate all tests to new test infrastructure

plugins/kotlinx-serialization/testData/codegen/Basic.kt

@@ -1,4 +1,4 @@
-// CURIOUS_ABOUT serialize, deserialize, write$Self, childSerializers, <init>, <clinit>, getDescriptor
+// CURIOUS_ABOUT: serialize, deserialize, write$Self, childSerializers, <init>, <clinit>, getDescriptor
 // WITH_STDLIB
 
 import kotlinx.serialization.*
@@ -10,4 +10,4 @@ class User(val firstName: String, val lastName: String)
 class OptionalUser(val user: User = User("", ""))
 
 @Serializable
-class ListOfUsers(val list: List<User>)
+class ListOfUsers(val list: List<User>)