feat(plugin/page_vote): add `page_vote` plugin

[Liumingxun]

I believe the "vote up/down page" button should be appended to a specified element. Style and update vote count still have some problem, but it's a work in progress.

Feel free to discuss with me and share your thoughts.

close #944

[qwqcode]

Thank you for your PR. You provided me with a design idea for this feature. I took some time to think and made some modifications based on your code, including:

• Support for voted state style options (pageVote.activeClass)
• Support for custom element selectors (pageVote.upBtnEl, etc.)
• Prevent users from setting pageVote on the client from the Dashboard
• Execute cleanup during unmounting
• Added some documentation

I have performed some basic manual testing on the frontend.

If you have any additional insights or suggestions, I’d love to hear them! Feel free to discuss! 😉