fix(module:time-picker): allow inputting string type

[wenqi73]

Fixes #4775
Fixes #4777
Fixed #4871

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?

[X] 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
[x] No

Other information

[codecov]

Codecov Report

Merging #4949 into master will increase coverage by 0.00%.
The diff coverage is 85.71%.

@@           Coverage Diff           @@
##           master    #4949   +/-   ##
=======================================
  Coverage   91.55%   91.55%           
=======================================
  Files         535      535           
  Lines       13686    13692    +6     
  Branches     2043     2045    +2     
=======================================
+ Hits        12530    12536    +6     
+ Misses        693      690    -3     
- Partials      463      466    +3     

Impacted Files	Coverage Δ
components/i18n/date-helper.service.ts	87.50% <66.66%> (+0.65%)	⬆️
...ponents/time-picker/time-picker-panel.component.ts	92.88% <100.00%> (-0.73%)	⬇️
components/time-picker/time-picker.component.ts	94.00% <100.00%> (+0.18%)	⬆️
...nents/time-picker/time-value-accessor.directive.ts	91.30% <100.00%> (ø)
components/core/util/text-measure.ts	89.56% <0.00%> (-1.74%)	⬇️
components/time-picker/time-holder.ts	96.64% <0.00%> (-0.68%)	⬇️
components/table/src/table/tr-measure.component.ts	100.00% <0.00%> (+13.04%)	⬆️
components/table/src/table/tbody.component.ts	100.00% <0.00%> (+14.28%)	⬆️

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