Widget: Checkbox Group

### Description

Implemented in Dashboard 1.0, but only as part of it's "Form" widget. We may also want a standalone 'checkbox Group" widget too, although could be replicated by adding a collection of Toggles (#42) into a single group within a age Layout.

### Properties

- Label/description
- List direction (vertical/horizontal)
- List of options to include and their respective label/value

### Events

- **on-change**: this widget would need to send a message back to Node-RED when it's value is changed/updated

### Controls

- **enabled**: this widget can be enabled/disabled

### Existing Examples

Vuetify: https://vuetifyjs.com/en/components/checkboxes/

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate