Zoraxy - add option for -fastgeoip=true

[AdmiralAwesome]

Hey,
in this update: https://github.com/tobychui/zoraxy/releases/tag/2.6.6 (previous one from the current version which is 2.6.7) by default -fastgeoip=true is diabled.

It would be an awesome option for the script, to allow selecting if I want to have this option enabled or not. In a nutshell - you can choose if you want to use more CPU power or increase memory usage.

Notes regarding low / high speed GeoIP lookup mode
Zoraxy will try to resolve and store the visitors country of origin in its statistic collector. As requested by users regarding the memory usage issue, we added a low speed mode for GeoIP lookup logic to reduce memory usage by space time tradeoff. The low speed mode (default mode) of GeoIP lookup will slow down each request by around 6ms, which is not significant in homelab / self hosting environment. However, if you plan to use Zoraxy in production environment, you can enable to high speed mode by using -fastgeoip=true. We also optimized the high speed mode data structure so it now use around 600 - 700MB of RAM instead of 1.2GB. If your server have that capacity to run in high speed mode, we generally recommend using high speed mode for better user experience.