refactor: bls_aggregation new struct TaskSignature

[damiramirez]

What Changed?

This PR introduces a small refactor by encapsulating related parameters into a new struct and simplifying function interfaces.

• Create a new struct TaskSignature with a constructor method. This struct encapsulates the parameters used by ProcessNewSignature().

type TaskSignature struct {
	taskIndex types.TaskIndex
	taskResponse types.TaskResponse
	blsSignature *bls.Signature
	operatorId types.OperatorId
}

func (a *BlsAggregatorService) ProcessNewSignature(ctx context.Context, task TaskSignature) error

• Update BlsAggregationService interface with the new signature.
• Adjusted test cases to align with the new function signatures.

Reviewer Checklist

• Code is well-documented
• Code adheres to Go naming conventions
• Code deprecates any old functionality before removing it