Problem serializing some Kueue types for logging

[gabesaba]

What happened:
Observing error messages like the following in logs:

"nominatedAssignmentError": "json: unsupported type: resources.FlavorResourceQuantities"
"resourcesError": "json: unsupported type: resources.FlavorResourceQuantities"
"resourcesRequiringPreemptionError": "json: unsupported type: sets.Set[[sigs.k8s.io/kueue/pkg/resources.FlavorResource](http://sigs.k8s.io/kueue/pkg/resources.FlavorResource)]"
"usageError": "json: unsupported type: resources.FlavorResourceQuantities"

here are the lines, corresponding to v0.10.0

cache/snapshot.go:64
cache/snapshot.go:73
preemption/preemption.go:346
scheduler/logging.go:43

What you expected to happen:
These types should be serialized properly

How to reproduce it (as minimally and precisely as possible):
Run integration tests with higher log verbosity, grep for json: unsupported type

Anything else we need to know?:
The scope of this bug includes identifying other types we fail to serialize - the list above is not necessarily exhaustive - and fixing those too

Environment:

• Kueue version (use git describe --tags --dirty --always): v0.10.0