WatchFaceAnalog: local date/time variables

Use local date and time variables. No need to store them in the object.

The clock app only reads from the dateTimeController, never modifies it.

Remove unused `ScreenList.h` include.

For `std::abs()` add needed include `<cmath>`.

For the forward declared Settings-Controller add the `Settings.h`
include to the cpp file.

Don't use relative imports like `../foo.h` as those depend on the
relative position of both files. Rather than that use imports relative
to the `src` directory, which explicitly is part of the include
directories.