feat(module:form): support hide the label colon

[hsuanxyz]

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• Tests for the changes have been added (for bug fixes / features)
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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

Sync ant-design/ant-design#15276
Ref ant-design/ant-design#15585

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[codecov]

Codecov Report

Merging #3136 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3136      +/-   ##
==========================================
+ Coverage   97.48%   97.48%   +<.01%     
==========================================
  Files         607      607              
  Lines       11870    11894      +24     
  Branches      867      867              
==========================================
+ Hits        11571    11595      +24     
  Misses        190      190              
  Partials      109      109

Impacted Files	Coverage Δ
components/form/nz-form-label.component.ts	100% <100%> (ø)	⬆️
components/form/nz-form-item.component.ts	100% <100%> (ø)	⬆️
components/form/nz-form.directive.ts	100% <100%> (ø)	⬆️

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[TheAifam5]

Would be not better to name it as “nzShowColon” and set it to “true” as default?

Its just a idea.

[hsuanxyz]

@TheAifam5 thanks for your suggestion, but we want boolean attributes default value is false.

https://www.w3.org/TR/html5/infrastructure.html#sec-boolean-attributes

A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.

[vthinkxie]

LGTM