Add probabilistic weather

[wenzeslaus]

• New probabilistic weather is determined by distribution parameters.
• Load weather by its step into buffer for all simulation steps in chunk. Add weather from distribution.
• Stochastic runs share deterministic weather (both value and data), but each has its own instance of probabilistic weather.
• Use enum to check weather instead of a string.
• Work with no weather as a default type (implicit) and skip correctly any action based on that.
• Create schedules only after the weather is processed.
• Environment is now a single source of truth for weather.
• Make the weather optional (run function parameter is unresolved for probabilistic weather).
• Specify range for number of runs (must be greater than 1).
• Add stddev to data setup.
• Add tests for probabilistic weather. Update core to normal+uniform with checks.
• Update quarantine to not use suitable cells.
• Update config for OpenMP in Makefile to GRASS GIS 8.3.
• Move test weather data setup for later. In GRASS GIS 7.8, parallel creation of rasters does not work well in a new mapset (new versions have that fixed).
• Use curly brackets for statement spreading several lines
• Format code based on the new standard.