Plugin Development: Ability to modify panel time interval from Datasource code

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: Our datasource pulls telemetry data from Yamcs (a mission control software), and the timestamps can be in the past or future (simulations, replays, etc.). Panels always follow the dashboard time picker, so “Last 5 minutes” is based on real time instead of the simulation time coming from the datasource. Manually setting `timeShift` works, but there’s no way to set it automatically from the datasource code. **What would you like to be added**: A simple way for datasource plugins to override or adjust a panel’s time range at query time. This could be: - letting the datasource set `timeShift` / `relativeTime` programmatically, - or providing an API to return a custom time range based on the data. Either from the front-end or back-end. Also: is any of this possible with the current Grafana plugin APIs? If yes, a pointer to the interface or an example would help. **Who is this feature for?** Datasource developers working with simulated, replayed, or non-realtime data, where “current time” comes from the data, not the user’s system clock.