perf(module:radio): refactor radio group data flow

[vthinkxie]

PR Checklist

Please check if your PR fulfills the following requirements:

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

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] 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
[ ] No

Other information

[codecov]

Codecov Report

Merging #4770 into master will increase coverage by 0.04%.
The diff coverage is 98.33%.

@@            Coverage Diff             @@
##           master    #4770      +/-   ##
==========================================
+ Coverage   93.19%   93.24%   +0.04%     
==========================================
  Files         506      507       +1     
  Lines       12754    12752       -2     
  Branches     1962     1959       -3     
==========================================
+ Hits        11886    11890       +4     
+ Misses        454      450       -4     
+ Partials      414      412       -2

Impacted Files	Coverage Δ
components/radio/radio.module.ts	100% <ø> (ø)
components/radio/radio-group.component.ts	100% <100%> (ø)
components/radio/radio.service.ts	100% <100%> (ø)
components/radio/radio-button.directive.ts	100% <100%> (ø)
components/radio/radio.component.ts	97.01% <97.01%> (ø)

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