[BUG] Support referenced DTDL schemas

[rido-min]

PnP Properties defined in schemas, such as the ADU interface, are not rendered in the PnP views, with the error:

Unsupported field schema for field root: Unknown field type undefined.

Repro steps

Connect an ADU device reporting dtmi:azure:iot:deviceUpdate;1
Navigate to PnP Components, Agent

[YingXue]

Hi @rido-min
Can you help pointing me to any dtdl doc that has more explainations or samples regarding to how reference type works? I've searched through all the md file in this folder but couldn't find any: https://github.com/Azure/opendigitaltwins-dtdl/tree/master/DTDL

[rido-min]

lmk if this helps

https://github.com/Azure/opendigitaltwins-dtdl/blob/master/DTDL/v3/DTDL.v3.md#interface-schemas

I can also provide additional samples

[JedidiahPaterson]

I am seeing the same thing and also with other schemas that point to schemas defined in the "schemas"[] @YingXue is there another way to do what we need to do or is there any traction on this?