Allow for light/dark map styles for night and day which are selected automatically

This would not replace the ability to set a specific preference manually, but would be nice for most navigation applications.

* Defaults based on sunrise/sunset. This can be done using some astronomical calculations with Julian dates. I actually did something like this approximately forever ago: https://github.com/ianthetechie/NSDate-Julian. It looks like there are a few Rust crates doing something similar, so we can get it on all platforms: https://crates.io/crates/sunrise.
* In case the platform / app have ambient light data available, use this to switch to the dark style in the daytime (like Apple Maps when driving through a tunnel).