Pass along label/placeholder/registry for custom multiselect widgets.

[fsteger]

Reasons for making this change

Inconsistency between properties passed to custom select widgets. When widget is for a question of type string with an enum, the custom widget receives props for label, placeholder, and registry. When widget is used on a multi-select field, these properties are missing.

Sample Schema:

{
	type: 'object',
	properties: {
		selectQuestion: {
			title: 'Select Question',
			type: 'string',
			enum: ['foo', 'bar', 'baz', 'qux'],
			enumNames: ['foo', 'bar', 'baz', 'qux']
		},
		multiSelectQuestion: {
			title: 'Multi-Select Question',
			type: 'array',
			uniqueItems: true,
			items: {
				type: 'string',
				enum: ['foo', 'bar', 'baz', 'qux'],
				enumNames: ['foo', 'bar', 'baz', 'qux']
			}
		}
}

Sample UI Schema:

{
	selectQuestion: {
		'ui:widget': 'select'
	},
	multiSelectQuestion: {
		'ui:widget': 'select'
	}
}

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests
  • I've updated docs if needed
  • [X I've run npm run cs-format on my branch to conform my code to prettier coding style
• I'm adding a new feature
  • I've updated the playground with an example use of the feature

[epicfaace]

Thanks! The default MultiSelectWidget doesn't do anything with label/placeholder though -- do you think there is something we should do to change that?