feat(AppConfig): iterate how apps are managed

- auth clients are always shared, cannot be disabled
- custom connections are enabled by default, can be disabled
- any existing connections can be reconnected regardless of its AppConfig or AppAuthClient states

packages/backend/test/mocks/rest/api/v1/apps/create-connection.js

@@ -2,7 +2,6 @@ const createConnection = (connection) => {
   const connectionData = {
     id: connection.id,
     key: connection.key,
-    reconnectable: connection.reconnectable || true,
     appAuthClientId: connection.appAuthClientId,
     formattedData: connection.formattedData,
     verified: connection.verified || false,