feat(module:divider): variant

[ParsaArvanehPA]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] 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 we lack the variant feature of the Divider compoent that Ant Design supports.

What is the new behavior?

Variant is implemented

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

Since Ant has kept the dahsed option as a prop of the divider component, the nzDashed is also not deleted.