Fix tuple BnB metric ordering propagation

[EliteCoder18]

Tuple BnB metrics currently propagates requires_ordering_by_descending_value_pwu() using all().

If one metric requires descending order and another does not, order is skipped, thus violating the requirement of the order-dependent metrics.

What this PR does:

1. Adds a test (bnb_tuple_metric_respects_ordering_requirement) demonstrating the issue.

2. The fix involves changing the ordering propagation to use any() instead of all().

The test is added in a separate commit to clearly demonstrate the failing behavior before the fix.

[evanlinjin]

Thanks for the fix! Before ACK/Merge, I propose the following changes:

1. Simplify tests

No need to actually run .bnb_solutions. We just need to make sure ((metric_a, 1.0), (metric_b, 1.0)).requires_ordering_by_descending_value_pwu() returns the correct value.

• score and bound implementations of OrderSensitive and NoOrderMetric can just return Some(Ord32(0.0)).
• Have the following test cases:
  • Both metrics require ordering
  • One metric requires ordering
  • No metric requires ordering

2. Don't have a separate clippy/lint commit

Just merge the commits.

[EliteCoder18]

Thanks for the suggestions. I've made the tests easier by only covering the three ordering situations and getting rid of the lint commit.

Please let me know if anything else needs to be changed

[evanlinjin]

Don't forget to do cargo fmt and cargo clippy otherwise CI will fail.

[evanlinjin]

ACK 66e82d4