Multiple cmaps for prediction plots

For `deepsensor.plot.prediction`, users should declare multiple Colormap objects in `cmap` according to the elements in `prediction_parameters`.

https://github.com/alan-turing-institute/deepsensor/blob/ca376d888fa0c685cc9dabbbd3e7d35944b99fe5/deepsensor/plot.py#L860

Start in deepsensor/plot.py at the linked deepsensor.plot.prediction implementation and inspect how prediction_parameters and cmap are handled. Confirm the expected behavior from the issue image and verify that each prediction parameter can use its corresponding Colormap object in the resulting plots.

Written by the indexing model from the issue text.