server: support control vectors

[jakexcosme]

Note: This issue was copied from ggml-org#6316

Original Author: @phymbert
Original Issue Number: ggml-org#6316
Created: 2024-03-26T07:25:43Z

---

Motivation

It would be nice to support control vectors in the servers.

Requirements

• Configure gpt_params::control_vectors from common
• Tests the feature using the framework

References

• A first attemp has been made here: Control vectors in server ggml-org/llama.cpp#6289