(GH-3783) Add OnCommand and OffCommand to ToggleSwitch

[punker76]

Describe the changes you have made to improve this project

Add OnCommand and OffCommand properties to the ToggleSwitch. The previous ToggleSwitch had similar commands which allowed simple logic for this 2 states.

The command parameter for both commands will be the value of the CommandParameter or the ToggleSwitch if the property is null.

If the commands are not executable then the ToggleSwitch is still enabled, it will only disable the execuation.

e.g.

<Controls:ToggleSwitch CommandParameter="{Binding}"
                       OnCommand="{Binding ToggleSwitchOnCommand}"
                       OffCommand="{Binding ToggleSwitchOffCommand}" />

Closed Issues

Closes #3783

[fradsham]

Thank-you @punker76 . This is a great help.