Add support for UQ with conformal prediction

[radka-j]

Conformal prediction is well established for IID data, which is the majority of our current use cases. This should be a straightforward way to add principled UQ to the deterministic emulators (when there is enough data available for the calibration set).

[radka-j]

This will require holding out a calibration dataset. It's possible some of the logic for this will translate to implementing #589.

[radka-j]

Maybe have a look at this: https://github.com/awslabs/fortuna/tree/main