Update hello-nginx example for Lua Server SDK 2.0

[cwaldren-ld]

Our current hello-nginx is out-of-date and not compatible with the Lua Server SDK 2.0. For context, the Lua Server SDK was recently updated to make use of our new C++ Server-Side SDK.

Hello-nginx needs the same treatement that I recently applied to hello-haproxy:

• Archiving the old repo
• Updating the example to use the new SDK
• Adding it into this repo with CI