Add Prompt templating structures

[getnamo]

Not sure exactly how, but a better API for setting up various use cases:

• General chat interaction structure and reliable EOS tags
• Thought chains
• Assistant
• Roleplay
• External API calls e.g. a function call interpretation by LLM with injected results.

Base chat templating support e.g.

• ChatML
• Alpaca
• llama

[getnamo]

Add more robust support for templating with template lookup, see e.g. https://github.com/ggerganov/llama.cpp/wiki/Templates-supported-by-llama_chat_apply_template

[getnamo]

Also note jinja parsing is in: ggml-org/llama.cpp#11016

[getnamo]

with #33 this will be supported via Jinja mode using Jinja string:

Llama-Unreal/Source/LlamaCore/Public/LlamaDataTypes.h

Line 202 in 387e0e7

FString Jinja = TEXT("");