C# client and Lua script combo for storing per-entity logs in Redis

Lua script will take:

• Key
• Appendage
• Last-Known-Length

It will guarantee that:

• writes only happen if the given Last-Known-Length is correct

C# client will:

• try to execute script by hash
  • upload script if missing
  • execute script
• return handle to stream

TESTING:

• The Lua script will be integrated with the client - ie the client will upload the script
• So, we can just test the client in its target language, C#
• But then the tests need some control over Redis, maybe via docker
• So, C# tests must load dockerized Redis

If an LKL is wrong, then the client must re-read. In the future maybe the server can serve the extra data back, but for now...