- Added Gitlab::Ci::Config::Entry::Rules and Gitlab::Ci::Config::Entry::Rules:Rule
  to handle lists of Rule objects to be evalauted for job inclusion
- Added `if:` and `changes:` as available Rules::Rule::Clause classes
- Added Rules handling logic to Seed::Build#included? with extra specs
- Use DisallowedKeysValidator to mutually exclude rules: from only:/except: on job config