NeumorphicSwitch implementation

[almighty972]

The first usable version of the NeumorphicSwitch widget is implemented.
The track and the thumb are built from a Neumorphic widget.

NeumorphicSwitch can take a NeumorphicSwitchStyle as input.
You can provide these values to the NeumorphicSwitch through the NeumorphicSwitchStyle:

• depth
• concaveShape
• activeTrackColor
• inactiveTrackColor
• activeThumbColor
• inactiveThumbColor

If no NeumorphicSwitchStyle is provided, the switch will use the default theme values.

To use NeumorphicSwitch (emboss mode):

    NeumorphicSwitch(
          value: _switchEnable,
          style: NeumorphicSwitchStyle(
              depth: -3, 
              concaveShape: false,
          onChanged: (value) {
            setState(() {
              _switchEnable = value;
            });
          },
    )

To use NeumorphicSwitch (concave mode):

    NeumorphicSwitch(
          value: _switchEnable,
          style: NeumorphicSwitchStyle(
              concaveShape: true,
          onChanged: (value) {
            setState(() {
              _switchEnable = value;
            });
          },
    )

[florent37]

I think the Thumb might be concave / convex
as tried

[florent37]

only the "background" is embossed

[florent37]

or the thumb is flat with more elevation than the background

[florent37]

looks like yours :)