Monitors introduced as method to output data from microphysics

[yoctoyotta1024]

Similar to detectors from earlier in CLEO's history, concept of "monitors" created for observers to output data collected from within running of SDM, e.g. total mass of condensate condensed per timestep, or precipitation rates.

• placeholder for detectors in gridboxes removed
• MicrophysicalProcess concept expanded to add use of monitors to run_step constraint
• Null, Combined and Condensation types satisyfying monitors concept implemented

also:

• Use of traits for writing datatype strings in xarray metadata, e.g. dtype="<f4" created from float instantiation of templatde metadata type.
• xarray and zarr metadata put in seperate files
• a few more uses to auto