* prepo: Implement calls of IPrepoService
- Implement `SaveReportOld`, `SaveReportWithUserOld`, `SaveReport`, `SaveReportWithUser` not accurate by RE (except for result codes). It's here to do something with the data since we will never use the `Play Report` sent by the game. So it's better than just a stub.
- Fix a typo in `ldn` result code.
Close#807
* Add a processing method
* Address some comments
* remove unneeded using
* Resolve requested changes
* Typo
* Update IPrepoService.cs
