Pre-process data of water vapour

[SarahAlidoost]

in #78, we added a script to preprocess and store the data in zarr for variable sst. we want the same for water vapour. To do:

• look at the data preparation scripts and create new scripts for water vapour: perhaps add the name of the variable to the script name.
• check with the project partners about the spatial coverage of the data, and resolution, then adjust the data preparation scripts.
• after data preparation, move the data to project dir.

note: this is needed for training and not tuning. Tuning uses 1 year data and it fits in memory.