[API] Add ML LXM Service API(internal) for large model interactons

[songgot]

This commit introduces the ML LXM Service API, a new C API designed to facilitate interactions with large-scale models such as Large Language Models (LLMs)

[hj210]

This API has a solid foundation and demonstrates clear design goals
and consistent implementation. It is particularly well-aligned with
its specific purpose of interacting with LLMs/LVMs.
With some small refactoring, it could become cleaner and more maintainable code.

[hj210]

This function has a long parameter list. It would be better to reduce the number of parameters by using a structure type if possible.
For example,

typedef struct {
    const char *config_path;
    const char *instructions;
    ml_service_event_cb callback;
    void *user_data;
} ml_lxm_session_config_t;

int ml_lxm_session_create(const ml_lxm_session_config_t *config, 
                         ml_lxm_session_h *session) {
    if (!config || !session || !config->config_path || !config->callback)
        return ML_ERROR_INVALID_PARAMETER;
    
    return ml_lxm_session_create(config->config_path, config->instructions,
                                config->callback, config->user_data, session);
}

(This sample code is suggested by Cline)