Include/Exclude for custom properties

[ptemmer]

New Feature

Similar to the current behavior for labels, it would be nice to be able to exclude certain custom properties.

custom-properties:
  include:
    - name: ruleset-tier
       value: strict

  exclude:
    # ignore (don't delete) the following custom-properties
    - name: team

This way certain custom-property values that are organization-wide can be enforced, while others that are required to be set, but have different value per repo, will be left untouched.