Add Northflank connection support

- Introduced Northflank as a new app connection option, including API token authentication.
- Implemented connection schemas, validation, and service functions for Northflank.
- Updated API documentation to include Northflank endpoints and integration instructions.
- Added frontend components for creating and managing Northflank connections.

backend/src/services/app-connection/northflank/northflank-connection-service.ts

@@ -0,0 +1,31 @@
+import { logger } from "@app/lib/logger";
+import { OrgServiceActor } from "@app/lib/types";
+
+import { AppConnection } from "../app-connection-enums";
+import { listProjects as getNorthflankProjects } from "./northflank-connection-fns";
+import { TNorthflankConnection } from "./northflank-connection-types";
+
+type TGetAppConnectionFunc = (
+  app: AppConnection,
+  connectionId: string,
+  actor: OrgServiceActor
+) => Promise<TNorthflankConnection>;
+
+export const northflankConnectionService = (getAppConnection: TGetAppConnectionFunc) => {
+  const listProjects = async (connectionId: string, actor: OrgServiceActor) => {
+    const appConnection = await getAppConnection(AppConnection.Northflank, connectionId, actor);
+    try {
+      const projects = await getNorthflankProjects(appConnection);
+
+      return projects;
+    } catch (error) {
+      logger.error(error, "Failed to establish connection with Northflank");
+      return [];
+    }
+  };
+
+  return {
+    listProjects
+  };
+};
+