feat: Cedar annotation to specify description of Policy

[reste85]

Adding the possibility to define an annotation @cdkDescription inside the policy's definition statement/file in order to specify the description it will have in CloudFormation Resource. Current implementation is considering the annotation in every case (both from fromFile method and when using directly the Policy construct)

• Policy construct description precedence:

  • If description is present in the construct properties --> we keep this
  • If not, we try to search the contents of annotation

• fromFile description precedence:

  • If description is present in the properties --> we keep this
  • If not, we try to search the contents of annotation
  • If the annotation is not present we keep the basePath of file