Add new `SUB_TYPE` field to `type: ITEM` (MAPCO-5084)

For `ITEMS`, we have added new `SUB_TYPE` property in order to distinguish between different types of control_points.
possible values are now:
1. CONTROL_CROSS
2. CONTROL_INFRASTRUCTURE
3. CONTROL_POINT

We need to add it to our mock data, to `generateDisplayName` control response function, and to the config's `application.controlObjectDisplayNamePrefixes`

Start by locating the mock data, the generateDisplayName control response function, and the configuration entry application.controlObjectDisplayNamePrefixes. Add support for the three listed SUB_TYPE values in each location, then verify that generated control display names and configuration behavior reflect the new field.

Written by the indexing model from the issue text.