Add generate_query_fragments configuration option

[trevor-scheer]

Closing the loop on apollographql/federation#2958

• I'm unsure if override + log warning is the appropriate action, do we have a similar pattern in config elsewhere?
• Is there a place where the yaml config options are all documented? I don't see anything existing for reuse_query_fragments.
• How to test the log warning was emitted?

[router-perf]

CI performance tests

• reload - Reload test over a long period of time at a constant rate of users
• events_big_cap_high_rate_callback - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity using callback mode
• events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
• large-request - Stress test with a 1 MB request payload
• const - Basic stress test that runs with a constant number of users
• no-graphos - Basic stress test, no GraphOS.
• step-jemalloc-tuning - Clone of the basic stress test for jemalloc tuning
• events - Stress test for events with a lot of users and deduplication ENABLED
• events_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• events_big_cap_high_rate - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity
• events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• xxlarge-request - Stress test with 100 MB request payload
• xlarge-request - Stress test with 10 MB request payload
• step - Basic stress test that steps up the number of users over time

[BrynCooke]

Looks like documentation still needs updating.

[trevor-scheer]

@BrynCooke I added some docs for the new option as well as the existing option since they're pretty related. Let me know if you have any opinions on where the new section belongs, if you think it should go somewhere that isn't where I put it.

[Geal]

the failing integration tests could be due to a cache key changing with the option https://app.circleci.com/pipelines/github/apollographql/router/20059/workflows/bf8a774f-1e0d-49eb-a5ec-4324d6ac90f0/jobs/134413

[trevor-scheer]

Thank you both!