Handle ThingDescriptions as streams

In the 08/03 call, we briefly explored the idea of handling Thing Descriptions as Streams. The discussion was originally brought up by the latest advancements in WoT Profiles and WoT Discovery. In particular, this issue is linked to the idea of a minimum supported hardware platform for WoT and Handle big TDs or set of TDs.

As discussed in the call we don't have a well-defined use case extracted for those issues, but the main idea is to allow a possible consumer application to read a TD incrementally. We have pinpointed three possible places that we'll need to be updated: the getThingDescription, consume, and the discovery method.

Notice that in Scripting API the only method to fetch TDs is using the discovery method. Furthermore, if we don't want to force the implementation to store everything in memory the method getThingDescription should be modified to return a stream and the consume method too. About this last point, my conjecture is that is possible to read a TD incrementally and create a ConsumeThing without having the whole TD always stored in some memory buffer.

Still, we find that the issue needs concrete examples where the current API design fails. The optimal would be having a concrete board or hardware as an example.

Start by reviewing the linked WoT Profiles issue and WoT Discovery issue, then examine the getThingDescription, consume, and discovery methods in the Scripting API. Define a concrete board or hardware use case where the current API fails and document the required streaming behavior before attempting implementation.