[feature]: Unify integration actions into the automation engine

Is there an existing issue for this? • I have searched the existing issues Summary Today, integrations such as GitLab and GitHub have their own specific configuration for actions like changing a work item state based on Pull Request or Merge Request events. This works for simple use cases, but it limits the potential of integrations. The proposal is to separate the integration setup from the workflow behavior: • Integrations should only connect external systems and expose events. • Plane Automations should define what happens when those events occur. This would make integrations more flexible, reusable, and consistent across different tools. Why should this be worked on? --- Current behavior Currently, when configuring an integration, some automation behavior is configured inside the integration itself. Example: • Connect GitLab • Connect GitHub • Configure automatic state changes directly inside the integration settings • The in…