text: Title: Explain query planning
  Body: Make a concise print function for the `QueryPlanningAnalysis` class https://github.com/kensho-technologies/graphql-compiler/blob/v2.0.0.dev25/graphql_compiler/cost_estimation/analysis.py#L381
  
  In most cases, the printout of the analysis passes is enough to explain why a particular query plan was chosen.