feat: public namespace basic function

[youabcd]

What's the purpose of this PR

Created a basic administration page for public namespaces. All public namespaces are displayed on the page and click items to jump to the actual editing page.As shown in the figure below:

The original left column of the page in English mode was not aligned, now it is modified to be aligned.

Which issue(s) this PR fixes:

Fixes #1926

Brief changelog

first commit
The function in namespaceController is called to take out and display all the public namespaces in the database.

second commit
Make simple changes to the page style.

third commit
Based on the suggestions to make changes.

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[youabcd]

I have read the CLA Document and I hereby sign the CLA

[nobodyiam]

Please see some comments below.
BTW, would you please follow the pull request template to add more information about this PR?
It would also be great if some screenshots could be provided.

[youabcd]

I have made some changes based on suggestions.

[nobodyiam]

Thanks, I think this is a small milestone achieved!
BTW, I kind of like your original design about the home page by displaying these items in one table, will you keep working on this?

[youabcd]

I have changed the grid display to a table display and also changed the left bar to a menu, as shown below:

[codecov-commenter]

Codecov Report

Merging #3850 (fbbeb8f) into master (982a01f) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #3850   +/-   ##
=========================================
  Coverage     51.55%   51.55%           
  Complexity     2529     2529           
=========================================
  Files           484      484           
  Lines         14806    14806           
  Branches       1533     1533           
=========================================
  Hits           7633     7633           
  Misses         6646     6646           
  Partials        527      527           

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[nobodyiam]

I tested this feature in my local environment and it looks great! Keep going!

[nobodyiam]

BTW, I really like the style of your original design, is it possible to adjust the colors, layouts, search boxes to look like below?

[nobodyiam]

Looks much better now. Please find some comments below.

[nobodyiam]

Basically I think it's good to go. Please solve the remaining issues and update the latest master branch. Then we could invite more people to review.

BTW, please also update the CHANGES.md.

[nobodyiam]

@youabcd Looks great now, all the pending issues are resolved! Please update the CHANGES.md and I think we are good to go.

[nobodyiam]

LGTM