feat(module:notification): support for more custom templates

[HyperLife1119]

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?

Issue Number: N/A

1. 要想自定义按钮，必须传递整个 Notification 模板。
2. 不支持 title / content 模板

What is the new behavior?

1. 使用 nzButton 实现自定义按钮。
2. 支持 title / content 模板

Does this PR introduce a breaking change?

[x] Yes
[ ] No

一个微小的破坏性变更：
在使用字符串作为 title/content 时，ant-notification-notice-message 与 ant-notification-notice-description 的内部会增加一层 div 节点

这可能会破坏用户自定义的 CSS 选择器（子节点选择器）:

.ant-notification-notice-message > x { }
.ant-notification-notice-description > x { }

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 (fa0312a) 91.64% compared to head (f98335e) 91.69%.
Report is 60 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8046      +/-   ##
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+ Coverage   91.64%   91.69%   +0.04%     
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  Files         515      519       +4     
  Lines       17640    17857     +217     
  Branches     2790     2735      -55     
==========================================
+ Hits        16167    16374     +207     
- Misses       1175     1184       +9     
- Partials      298      299       +1     

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[Nicoss54]

LGTM! @simplejason could you take a look

[HyperLife1119]

This PR contains breaking changes and we should merge it before v17 is officially released. @simplejason @OriginRing

[HyperLife1119]

我决定保留 NzNotificationService#template() 用法，作为 zorro 的一种特色功能存在。