feat(module:drawer): return componentRef when nzContent is a component

[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?

As Angular is constantly evolving, we can do now a lot of things with the componentRef. In this idea in mind, it coud be a good idea to expose the componentRef when the nzContent is a component.

Issue Number: N/A

What is the new behavior?

Now thanks to the getContentComponentRef function expose by the drawerRef. Developer have the possibilities to retrieve the componentRef of the nzContent in a readonly mode

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (df766b6) 91.73% compared to head (92612f0) 91.73%.
Report is 1 commits behind head on master.

Additional details and impacted files

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  Files         520      520           
  Lines       18010    18014    +4     
  Branches     2838     2838           
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+ Hits        16521    16525    +4     
  Misses       1186     1186           
  Partials      303      303           

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[HyperLife1119]

LGTM

[Nicoss54]

@HyperLife1119 Are you ok to merge this PR ? Then i will do the same for the modal