docs: setup translation infra

[Jinjiang]

• contributing docs
• updated npm scripts
• added 2 script files vitepress-translation-helper for comparing translation checkpoints and generating translation info (same as refactor: replace translation scripts and ui with vitepress-translation-helper router#2109)
• added translation status UI
• upgraded vitepress to rc35 rc36

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ebbb02f) 89.53% compared to head (f6bd586) 89.53%.
Report is 3 commits behind head on v2.

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Additional details and impacted files

@@           Coverage Diff           @@
##               v2    #2549   +/-   ##
=======================================
  Coverage   89.53%   89.53%           
=======================================
  Files          11       11           
  Lines        2875     2875           
  Branches      232      232           
=======================================
  Hits         2574     2574           
  Misses        285      285           
  Partials       16       16           

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[awxiaoxian2020]

vitepress rc36 released 17 hours ago, should we upgrade to rc36?

[Jinjiang]

vitepress rc36 released 17 hours ago, should we upgrade to rc36?

I upgraded to rc35 just because it supports rtl direction from that version. For other versions I personally don't mind that. However, I think it's not necessary and it could be a separated PR.

[Jinjiang]

@posva would you mind taking a look at this failing test, please? Since I think I didn't change anything related to this test but it failed after my commits. I also ran the same test locally and it succeeded. So I have no idea what is going on.

(and the rest of this PR is ready to review)

Thanks.