perf: run backtick code block in worker_threads

[SukkaW]

What does it do?

Try running backtick_code_block filter in worker_threads see what we could get.

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.

[github-actions]

How to test

git clone -b workerpool-before_post_render https://github.com/SukkaW/hexo.git
cd hexo
npm install
npm test

[renbaoshuo]

@hexojs/core

This PR is outdated after merging #5095, should we close this PR or update and merge it before merging #5092?

[SukkaW]

Just close it. The PR is initially a PoC, which turns out does not work anyway.