Start llama.cpp server

[dnhkng]

This PR adds starting the llama.cpp server with parameters taken from the config file.

As the parameters are in the same position as those from the ooba process, the name has been refactored from 'ooba_params' to 'server_params'.

The server is started and stopped using subprocess, but tries to follow a similar style as the code for ooba.

Note: This requires you pull and compile llama.cpp first!

[sam-paech]

Thanks for this! I want to make a few changes to this before merging:

• resolve relative paths (~)
• add same functionality as the ooba class (download model etc)
• set --ctx-size 1024+, throw error if user sets this arg less than 1024 in config

I'll let you know when I have a chance to start working on this, or if you want to do this please feel free.

[dnhkng]

- set --ctx-size 1024+, throw error if user sets this arg less than 1024 in config
Seems easy, I can add this.

resolve relative paths (~)
To the model? to the executable?

add same functionality as the ooba class (download model etc)
Probably best if you take care of this, as I'm not sure of the details.