refactor(theme/view): replace lodash

[curbengh]

What does it do?

Testing for this code snippet, as an attempt to revive #3807.

How to test

git clone -b BRANCH https://github.com/USER/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 (+0.003%) to 97.141% when pulling 4104778 on curbengh:view-lodash into e4a5292 on hexojs:master.

[curbengh]

Object.assign() really can't handle on large object well.