[Feat/Fix] Refactoring Llava models into single file

[Luodian]

This PR includes the addition of new model classes for handling different configurations.

Key Changes

1. Introduced LlavaQwenForCausalLM and LlavaMistralForCausalLM classes, extending the LlavaLlamaForCausalLM with specific configurations for Qwen2 and Mistral models respectively.

2. Modified the model_runner.py to refactor the entry class definition to To support multiple model classes in one module (we make different llava with different llms into one module to clean the code).

Fix

1. We fix small template issues in example usages of llava_qwen and llava_llama3 model

[Luodian]

This is my test, after refactoring, llava_qwen and llava_llama3 works correctly. (please ignore the output of the template message, it's for debug and removed in commit.)

[Luodian]

@merrymercy @BabyChouSr @Qubitium

Thanks for maintaining such wonderful project. Please check this PR and feel free to give more suggestions, thanks!