Connect logic in Workspace Entity Manager (#13078)

Large PR, sorry for that. Don't hesitate to reach me to have full
context (env. 500lines for integration and unit tests)

- Add connect logic in Workspace Entity Manager
- Update QueryDeepPartialEntity type to enable dev to use connect
- Add integration test on createOne / createMany
- Add unit test to cover main utils
- Remove feature flag on connect

closes https://github.com/twentyhq/core-team-issues/issues/1148
closes https://github.com/twentyhq/core-team-issues/issues/1147

packages/twenty-server/src/engine/core-modules/feature-flag/enums/feature-flag-key.enum.ts

@@ -8,6 +8,5 @@ export enum FeatureFlagKey {
   IS_IMAP_ENABLED = 'IS_IMAP_ENABLED',
   IS_MORPH_RELATION_ENABLED = 'IS_MORPH_RELATION_ENABLED',
   IS_WORKFLOW_FILTERING_ENABLED = 'IS_WORKFLOW_FILTERING_ENABLED',
-  IS_RELATION_CONNECT_ENABLED = 'IS_RELATION_CONNECT_ENABLED',
   IS_FIELDS_PERMISSIONS_ENABLED = 'IS_FIELDS_PERMISSIONS_ENABLED',
 }