Add Priority and PreemptionPolicy fields in ResourceBinding

[seanlaii]

What type of PR is this?
/kind api-change
/kind feature

What this PR does / why we need it:
Add SchedulePriority, Priority, and PreemptionPolicy fields in ResourceBinding to support priority-based scheduling. This enables:

• Priority-based scheduling for ResourceBindings
• Preemption control through PreemptionPolicy
• Better control over scheduling order of workloads across clusters

Which issue(s) this PR fixes:
Part of #5961

Special notes for your reviewer:

• Priority field is added as int32 to align with Kubernetes conventions
• PreemptionPolicy supports two modes: Never (default) and PreemptLowerPriority

Does this PR introduce a user-facing change?:

Add SchedulePriority, Priority, and PreemptionPolicy fields to ResourceBinding API to support priority-based scheduling and preemption control.
- Priority: Defines scheduling priority (higher values = higher priority)
- PreemptionPolicy: Controls whether binding can preempt lower priority bindings

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.34%. Comparing base (5bfdf61) to head (787679a).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5963      +/-   ##
==========================================
+ Coverage   48.33%   48.34%   +0.01%     
==========================================
  Files         666      666              
  Lines       54858    54858              
==========================================
+ Hits        26516    26522       +6     
+ Misses      26617    26613       -4     
+ Partials     1725     1723       -2     

Flag	Coverage Δ
unittests	48.34% <ø> (+0.01%)	⬆️

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