✨ Add Map driver

[rneswold]

Create a driver that provides a constant array of device values. It creates two devices: index accepts an integer and indicates which value in the internal array should get sent to the output device.

The configuration should take two parameters: values is an array of device value types that will be used. The driver might check that all the entries are of the same type because most devices only accept one type of value. The other parameter is error and represents the value to be placed at the output when the index device is out of range.

[rneswold]

Should this be a driver? Can one come up with a way that this functionality could be expressed in a logic block's expression? This array device would be writing to the back-end with every index change.

[rneswold]

Changing this from an "array" driver to a "map" driver. An array would imply a value for an index. In this map driver, a range of indices will map to a value. So the configuration will take an array of tables. Each table will have a start index value, an inclusive end index value, and the value to be emitted in the output device. If the end parameter is omitted, then the end is the same as start and the driver instance behaves like an array. The driver will need to make sure there's no overlap in the ranges.

Allowing a range to be mapped to a value means we can use the day of the year to pick a color for an LED light, for instance.

If a value doesn't fit in a range, the error value is emitted.