Weather phenomena icons

Related to utilities/kweather#73

Currently in KWeather (I'm a daily user of it), some icons are "basic" icons that should be used for other use-cases (such as up arrow for sunrise). So, it would be useful to get more weather-specific icons. Here's a list, based on the KWeather page :

• Wind icon : should be extracted from an icon such as weather-clear-wind
• Sunset/sunrise icon : maybe a simple sun + arrow, because the basic sunset icon could also mean sunrise.
• Humidity : currently it uses the temperature icon
• UV index : it uses a compass icon, maybe a needle in a sun or something like this would be better ?

Eventually, if new features come in the future :

• High/low tide icon : for tide hours ?
• Wave icon : if we are able to display the wave heights
• Windsock icon : if we can display the wind direction ?
• Snowflake : for snow layer height ?