`egui::Slider` is missing `max_decimals_opt` but the method is present for `egui::DragValue`

[polina4096]

Is your feature request related to a problem? Please describe. Basically as the title says, I see no reason why there is no max_decimals_opt for egui::Slider.

Describe the solution you'd like Implement a max_decimals_opt for egui::Slider. Should be really simple, internally it is already stored as Option<usize>.

Describe alternatives you've considered No alternatives.

Additional context No context.