instrumentation

Scaffold a complete New Relic Ruby agent instrumentation for a third-party gem in this repo. Use when the user asks to "instrument <gem>", "add instrumentation for <gem>", "scaffold a new instrumentation", or names a datastore / HTTP-client / messaging / AI-LLM gem and asks the Ruby agent to trace it. Generates the seven-file prepend+chain layout under lib/new_relic/agent/instrumentation/<name>/, a runnable…