Support searchable "select-one", add "select-many"

[Chris927]

As discussed with @Z92-K, we'd like to add the following:

const fields = [
  {
    type: 'select-one',
    name: '...',
    useSearch: true
  },
  {
    type: 'select-many',
    name: '...',
    useSearch: true
  }
]

We can implement select-one with carbon's ComboBox (if we need search), and select-many can be implemented via carbon's MultiSelect, where search can be enabled/disabled.