feat(module:modal): expose componentRef nzContent

[Nicoss54]

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
[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?

Currently modalRef don't expose the componentRef of nzContent which is too restricted. With the new API of Angular, user must have he possibilities to retrieve the ref of the component of nzContent to use for exemple APIs like setInput

Issue Number: N/A

What is the new behavior?

Now ModalRef expose the component Ref of the nzContent when nzContent is a component. This exposition is done by the mehtod getComponentRef which return the ref in a readonly mode

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f71162b) 91.74% compared to head (1bd9fa0) 91.75%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8389   +/-   ##
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  Coverage   91.74%   91.75%           
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  Files         520      520           
  Lines       18023    18028    +5     
  Branches     2838     2838           
=======================================
+ Hits        16535    16541    +6     
+ Misses       1185     1184    -1     
  Partials      303      303           

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[HyperLife1119]

Can you add Chinese documentation? :D

[Nicoss54]

Can you add Chinese documentation? :D

I'm sorry i don't speak chinese, but if you can give me the translation i will add it :)

[HyperLife1119]

Can you add Chinese documentation? :D

I'm sorry i don't speak chinese, but if you can give me the translation i will add it :)

Never mind, let's finish it in a subsequent PR.

@EnochGao Are you interested in translating this document? And #8339 :)

[HyperLife1119]

LGTM

[EnochGao]

Can you add Chinese documentation? :D

I'm sorry i don't speak chinese, but if you can give me the translation i will add it :)

Never mind, let's finish it in a subsequent PR.

@EnochGao Are you interested in translating this document? And #8339 :)

Ok, I will translate after the merger is successful. ^o^