fix(federation): correct order of @skip and @include conditions on the same selection

[goto-bus-stop]

PR https://github.com/apollographql/router/pull/6120 was the wrong solution. JS doesn't actually maintain the order of the conditions, like I thought. Instead, it always puts @skip first and @include second, the opposite of what Rust was doing.

https://github.com/apollographql/federation/blob/cc4573471696ef78d04fa00c4cf8e5c50314ba9f/query-graphs-js/src/pathContext.ts#L13-L33

The queries I was testing with just happened to pass in https://github.com/apollographql/router/pull/6120.

This changes the implementation of Conditions::from_directives to pick the directives out manually instead of iterating. Technically, this does two iterations of the directive list...but, the code is a bit simpler, I think.

In the second commit I do a small refactor to replace the is_negated boolean by a ConditionKind enum. I found it quite tricky to constantly translate the skip/include concepts to negation or not while reading the code, so I hope this simplifies it a bit.

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CI performance tests

• [ ] connectors-const - Connectors stress test that runs with a constant number of users
• [x] const - Basic stress test that runs with a constant number of users
• [ ] demand-control-instrumented - A copy of the step test, but with demand control monitoring and metrics enabled
• [ ] demand-control-uninstrumented - A copy of the step test, but with demand control monitoring enabled
• [ ] enhanced-signature - Enhanced signature enabled
• [ ] events - Stress test for events with a lot of users and deduplication ENABLED
• [ ] 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_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_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• [ ] events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• [ ] events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
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• [ ] reload - Reload test over a long period of time at a constant rate of users
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• [ ] step-with-prometheus - A copy of the step test with the Prometheus metrics exporter enabled
• [x] step - Basic stress test that steps up the number of users over time
• [ ] xlarge-request - Stress test with 10 MB request payload
• [ ] xxlarge-request - Stress test with 100 MB request payload