Add method for loading predictions into runners

[rwood-97]

Is your feature request related to a problem? Please describe.
At the moment there is no way to reload text predictions into the runners. This means if you want to e.g. georeference them or search them later on , you need to rerun the model.

It would be better if we could reload the predictions using a load_predictions method. This could ideally work at the patch/parent/geo levels.

Describe the solution you'd like
Add load_predictions method to the Runners

Describe alternatives you've considered
Temporarily as an alternative you can use pickle.
This obviously isn't ideal.