In preparation for the GTK4 port. This is just a cheap port, I'll implement proper entry completion after porting to GTK4.
All those properties were a waste compared to storing it into the context.
This commit brings a few changes that I was too lazy to split in different commits: * Remove a few useless arguments in the GcalWeatherService API * Move the weather management code from GcalWindow to GcalWeatherSettings * A few style changes