Add service for export dataset

app/api/views/download/service.py

@@ -0,0 +1,14 @@
+from .repositories import BaseRepository
+from .writer import BaseWriter
+
+
+class ExportApplicationService:
+
+    def __init__(self, repository: BaseRepository, writer: BaseWriter):
+        self.repository = repository
+        self.writer = writer
+
+    def export(self, export_approved=False) -> str:
+        records = self.repository.list(export_approved=export_approved)
+        filepath = self.writer.write(records)
+        return filepath