[Community CTransformers] Ability to use stream and astream

[QuentinBriand]

Checked

• I searched existing ideas and did not find a similar one
• I added a very descriptive title
• I've clearly described the feature request and motivation for it

Feature request

The feature is quite simple. Actually the CTransformers class doesn't integrate the methods _stream and _astream, what it does actually is switching silently (it seems weird for me that there isn't a proper log on the base LLM class to warn for such switches) to the invoke method.

Motivation

For business purpose i would want to be able to load gguf files with CTransformers while still being able to stream the responses via Langserve automatically or via custom SSE's and not get only a huge block at the end.

Proposal (If applicable)

I already added both of the functions into my own scripts but i don't know if i should post the code embed here as is.