fix: fixing full path in description of policy, adding AvpPolicyDescription annotation

[reste85]

• Added management of a new annotation AvpPolicyDescription which can be added on top of the policy in order to provide a description for it. We're following the rules here: https://docs.cedarpolicy.com/policies/syntax-policy.html

• Description priority is the follow:

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

Fixes #196