Handling default Padding Token and offer System Prompt

[carstendraschner]

hi @Psycoy This PR handles:

• not set padding tokens as it is a problem within e.g. LLAMA 3 8B Instruct. We set it per default to EOS token as this is an appropriate default token in inference.
• Additionally we offer setting of system props over arg as it influences models results and is petter an arg and not a hardcoded string

thank you for your efforts. kindest regards Carsten