Added SYSTEM QUERY RELOAD MODEL and SYSTEM QUERY RELOAD MODELS

Why it matters

These commands solve the problem of updating or refreshing machine learning models dynamically, allowing users to apply changes to models without downtime or restarting the ClickHouse server, which improves operational efficiency and usability.

How to use it

Use the command SYSTEM QUERY RELOAD MODEL <model_name> to reload a specific model or SYSTEM QUERY RELOAD MODELS to reload all models at once within the ClickHouse client or query interface.