feat(enhance_cache): bring up [locals]

[SukkaW]

What does it do?

This PR is a part of #3897. When enhance_cache is enabled, partial will enable fragment_cache result unless theme developer specific { cache: false } or the locals has changed.

How to test

git clone -b feat_enhance_cache https://github.com/sukkaw/hexo.git
cd hexo
npm install
npm test

Screenshots

Pull request tasks

• Add test cases for the changes.
• Passed the CI test.

[coveralls]

Coverage increased (+0.004%) to 97.139% when pulling 38175d6 on SukkaW:feat_enhance_cache into e423773 on hexojs:master.