Step 3 - Add MetricsTracer to Graphql Schema

• DRAFT: Full Context MR
• Step 1.1 - Create graphql_known_operations from webpack plugin
• Step 1.2 - Add ApplicationContextTracer to Graphql Schema
• Step 2 - Add LoggerTracer to Graphql Schema
• Step 3 - Add MetricsTracer to Graphql Schema

What does this MR do and why?

This MR introduces a MetricsTracer for the Graphql Schema which writes Metrics::Sli events for every execute_query.

Screenshots or screen recordings

Taken from /-/metrics locally.

How to set up and validate locally

1. Start gdk
2. Visit an issue#show page (which will trigger some GraphQL request)
3. Visit /-/metrics and search for graphql_query_apdex

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #331697 (closed)