make args.snpeff_jar_path optional

[ahmetsacan]

https://github.com/faryabiLab/Azurify/blob/c35262b21383b2acedac483afcea18af93cef638/azurify.py#L204C28-L204C48

• Make args.snpeff_jar_path optional.
• If user did not provide args.snpeff_jar_path, download snpeff and unzip in code (see the example in Ahmet's bmes.ahmet/sandbox.ipynb)