Introduce data source for discovery of device profile ID by name

```
data "apstra_device_profile_map" "all" {}
```

output would include a map of device profile attributes keyed by `id`

This is different from most other _plural-type_ data sources: those only return a list of ID.

This one needs to be different because we don't have a complementary _singular-type_ resource which can be used to retrieve the interesting details.