feat(module:statistic): support for loading state

[HyperLife1119]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[zorro-bot[bot]]

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.58%. Comparing base (81ef077) to head (c4c436e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8537   +/-   ##
=======================================
  Coverage   91.57%   91.58%           
=======================================
  Files         533      533           
  Lines       18336    18337    +1     
  Branches     2801     2801           
=======================================
+ Hits        16792    16794    +2     
  Misses       1226     1226           
+ Partials      318      317    -1     

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