Alpaca core whisper.cpp plugin

This is a wrapper of whisper.cpp implemented as per the discussion Integration of llama.cpp and whisper.cpp:

Use the whisper.cpp C interface
Reimplement the common library

Build

Important

When cloning this repo, don't forget to fetch the submodules.

Either: $ git clone https://github.com/alpaca-core/ac-local.git --recurse-submodules
Or:
- $ git clone https://github.com/alpaca-core/ac-local.git
- $ cd ac-local
- $ git submodule update --init --recursive