feat StayExport - Initial Implementation

- Created models for DB and DTOs: StayExportFile
- Added required db migrations.
- Added StayExportService and StayExportServiceFactory for stay exporting services.
- Added configuration options required for StayExport.

src/Somnia.GuestLog/Enums/Models/StayExportFileResult.cs

@@ -0,0 +1,9 @@
+namespace Somnia.GuestLog.Enums.Models;
+
+public enum StayExportFileResult
+{
+    OK = 0,
+    NoData = 1,
+    ExportError = 2,
+    UploadError = 3,
+}