feat: add option to disable meta generator tag

[curbengh]

What does it do?

Add meta_generator option (enabled by default) to disable addition of <meta name="generator" content="Hexo 3.9.0">.

Fix #3652 (comment)

How to test

git clone -b meta-generator https://github.com/curbengh/hexo.git
cd hexo
npm install
npm test

Pull request tasks

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

cc @JoeyBling

[coveralls]

Coverage increased (+0.0008%) to 97.153% when pulling 5d592cc on curbengh:meta-generator into 9b87047 on hexojs:master.

[yoshinorin]

It works well :)

IMO that it's nice if we disable meta_generator plugin here.

hexo/lib/plugins/filter/index.js

Line 14 in 9b87047

filter.register('after_render:html', require('./meta_generator'));

But, hexo ctx not yet load _config.yml settings when register filter/index.js.

[curbengh]

But, hexo ctx not yet load _config.yml settings when register filter/index.js.

good catch