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/connections/reset-connection.js

@@ -3,7 +3,6 @@ const resetConnectionMock = (connection) => {
     id: connection.id,
     key: connection.key,
     verified: connection.verified,
-    reconnectable: connection.reconnectable,
     appAuthClientId: connection.appAuthClientId,
     formattedData: {
       screenName: connection.formattedData.screenName,