Feature/auto confirmation filtering support

[strailov]

Summary

• Add AUTOCONFIRM field to TargetFields enum, enabling RSQL queries like AUTOCONFIRM==true and AUTOCONFIRM==false to filter targets by auto-confirmation
  presence
• Extend SpecificationBuilder with a boolean existence check for ONE_TO_MANY relationships — since autoConfirmationStatus is modeled as @OneToMany in JpaTarget
  (workaround for Hibernate lazy-loading on @OneToOne), the filter performs a LEFT JOIN and checks id IS [NOT] NULL
• Only == and != operators are supported; other operators and non-boolean values throw RSQLParameterSyntaxException