Extend supported ensemble probabilities for more variables

### What problem does your feature request solve?

Currently only `screen_level_temperature_probability_without_control.yaml` recipe exists, alongside relevant workflow tab for ensembles/probabilities.

There is a need for support to compute threshold-based probabilities for a wider range of variables (potentially for any variable a user might be interested in).

### Describe the solution you'd like

Anticipating a need to extend recipe functionality to be more 'generic' and accept variable name as input.
May need different ensemble probabilities recipes for pressure-level variables and model-level variables.
Consideration is needed to ensure workflow GUI can be flexible to support multiple variables.

### Describe alternatives you've considered