Added backend and fixed openapi generation

backend/src/main/resources/application.properties

@@ -0,0 +1,7 @@
+spring.application.name=AltitudeWeb
+database.name=${DB_NAME:web_db}
+database.port=${DB_PORT:3306}
+database.host=${DB_HOST:localhost}
+database.user=${DB_USER:root}
+database.password=${DB_PASSWORD:root}
+cors.allowed-origins=${CORS:http://localhost:4200}