Add container test for slider prompt

A few modifications were made while making this test:
- Change the "defaultMin/Max" to just be called "min/max", and pass the state through to make the inputs a controlled component. It is best to make form elements controlled since it makes it more clear how data flows.
- Force the passed in data to always be of type `number`, and transform it in the constructor to always be of type `string`, and change the onOk to transform it back to a number. With inputs, it is best to be very explicit about data types, and make it clear where you are using strings and where you are using numbers.
- Do not reset the state to `0` when the field is blank, that makes typing into it very hard (only applies after making it a controlled field)
- Use consistent booleans. Since the VM uses `isDiscrete`, change it so we do not use any opposite flags (like `decimal`) for clarity.

Writing tests for this really helped me understand the behavior. If you read through the test descriptions and see anything you did not intend, let me know.