<excludeAnnotations> added

[mk868]

Related #50

Adds so that rules can skip classes/members annotated with e.g. @Entity.

• New config option excludeAnnotations (comma-separated).
• Applies to requireSpecifiedNullness, verifyJSpecifyAnnotations, requireNullMarked.

For sample configuration

<configuration>
  <rules>
    <requireSpecifiedNullness>
      <excludeAnnotations>jakarta.persistence.Entity</excludeAnnotations>
    </requireSpecifiedNullness>
  </rules>
</configuration>

The following class will be ignored in analysis:

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.Id;

@Entity
public class UserEntity { // will be skipped

  @Id
  private String id;
  @Column(nullable = false)
  private String name;
  @Column(nullable = false)
  private String surname;

}