Add calendar support for multiple date selection (not date range)

## 🚀 Feature Proposal

The calendar component should have the ability to select multiple dates where a date range is not the use case. For example, a fitness class is offered every Friday, but I need to select which Fridays I will be attending the class.

## Motivation

We use the calendar component for booking single dates and date ranges, this use case is equally important in a booking context and is needed to make the calendar component useful.

## Example

For example, a fitness class is offered every Friday, but I need to select which Fridays I will be attending the class.