Built-in prompt compression

[vincentgiraud]

Optimization being part of prompt design, it'd be great to integrate a tool like LLMLingua in the VSC extension.

The prompty file could have a compression section:

compression:
    rate: 0.55
    target_token: 200
    ...

[wayliums]

I think this is a great idea. @sethjuarez what do you think?

[sethjuarez]

In general it should be able to be done in the render/parse step - maybe we could add an invoker for this?