feat: llamafile backend

[mudler]

Is your feature request related to a problem? Please describe.
llamafile seems to have quite of a speedup in terms of execution with CPU

Describe the solution you'd like
a llamafile backend

Describe alternatives you've considered
N/A

Additional context

[localai-bot]

Hello! It seems like you're looking to add a new feature to LocalAI. As mentioned, I'm a bot created by @mudler to help manage issues in this repository. I'll make sure your request gets on the radar.

Feature requests like this are very valuable, and I'll make sure that the team is aware of it. In case you haven't already, you might want to check if there are any similar requests that have

[BradKML]

How is this different than PowerInfer, and are there benchmarks out there addressing the speed increases for CPU? Similar question applies to Ollama and other API services