Include ECMWF Near Real Time Meteorological Forecast

[rohansaw]

Summary
Including ECMWF Near Real time (14days) forecasts.

• Forecasts can be activated with a parameter in the config
• Forecasts are not cached
• Forecasts are made either from the last date with valid data (in-season) or at the end of the cutoff date(met_end_date from the configuration).
• Step added as a seperate script to be executed conditionally within the fetch_metdata rule in Snakemake