refactor(module:typography): refactor

[hsuanxyz]

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
[x] 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

[codecov]

Codecov Report

Merging #4819 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4819      +/-   ##
==========================================
- Coverage   93.19%   93.18%   -0.02%     
==========================================
  Files         504      504              
  Lines       12731    12731              
  Branches     1959     1959              
==========================================
- Hits        11865    11863       -2     
- Misses        453      454       +1     
- Partials      413      414       +1

Impacted Files	Coverage Δ
components/typography/typography.module.ts	100% <ø> (ø)
components/typography/text-edit.component.ts	100% <ø> (ø)
components/typography/text-copy.component.ts	97.14% <ø> (ø)
components/typography/typography.component.ts	97.76% <ø> (ø)
components/core/util/text-measure.ts	89.56% <0%> (-1.74%)	⬇️

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[wenqi73]

LGTM