refactor the annual past exam paper module

[jiuxia211]

Due to the need to refactor fzuhelper, this module needs to be re-migrated to the new backend

[jiuxia211]

assign @penqee

[renbaoshuo]

Should we also build a PC version client (like a website) for this module? It might be more convenient.

[jiuxia211]

Now that the server has been refactored, we still need a PC version client to use, just like the splash page, so this issue is still open.