Support non-integer entries for Number Picker

[BinaryAssault]

Summary

The number picker currently only supports an integer. This limits the use case for decimal point numbers, say temperatures, money etc. Changing to a double allows for further versatility.

API Changes

Changes to SettingsView/Cells/NumberPickerCell.cs seems to be simple enough swapping int for double in the code.

 public static BindableProperty NumberProperty =
        BindableProperty.Create(
            nameof(Number),
            typeof(int?),
            typeof(NumberPickerCell),
            null,
            defaultBindingMode: BindingMode.TwoWay
        );

To

 public static BindableProperty NumberProperty =
        BindableProperty.Create(
            nameof(Number),
            typeof(double?),
            typeof(NumberPickerCell),
            null,
            defaultBindingMode: BindingMode.TwoWay
        );

etc

Intended Use Case

Would allow more versatility in the NumberPicker control without having to write a CustomCell anytime a double needed to be used for a NumberPicker