Allow users the ability to restore deleted flags

[silent1mezzo]

This allows users to restore delete flags from the main page.

Fixes #215 and partially solves #255

[silent1mezzo]

This is the first time working in Vue or Go so feel free to point out where I can improve the code.

[zhouzhuojie]

I'm wondering if using https://element.ele.me/#/en-US/component/collapse#collapse and wrap the new el-table with lazy loading can help improve the first page loading time, and also the restore deleted flags may not be a frequent usage to be always shown, what do you think?

[silent1mezzo]

@zhouzhuojie sounds good. I just updated it so it hides the Deleted flags and only loads them when a user clicks on the collapsed table.

[codecov-commenter]

Codecov Report

Merging #379 into master will decrease coverage by 0.15%.
The diff coverage is 70.00%.

@@            Coverage Diff             @@
##           master     #379      +/-   ##
==========================================
- Coverage   83.17%   83.01%   -0.16%     
==========================================
  Files          27       27              
  Lines        1736     1755      +19     
==========================================
+ Hits         1444     1457      +13     
- Misses        211      214       +3     
- Partials       81       84       +3     

Impacted Files	Coverage Δ
pkg/handler/crud.go	88.02% <68.42%> (-1.01%)	⬇️
pkg/handler/handler.go	83.63% <100.00%> (+0.30%)	⬆️

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[silent1mezzo]

Thanks for the catch on that API endpoint @zhouzhuojie

[zhouzhuojie]

Thanks for the contribution! I may tune a little bit for the css in the following PR, hope you don't mind.