fix(module:tree): fix icon to svg & draggable event listener

[simplejason]

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?

[x] Bugfix
[ ] 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: #2332 #2205 #2336

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #2338 into master will decrease coverage by 0.04%.
The diff coverage is 93.97%.

@@            Coverage Diff             @@
##           master    #2338      +/-   ##
==========================================
- Coverage   95.86%   95.82%   -0.05%     
==========================================
  Files         485      485              
  Lines       12241    12274      +33     
  Branches     1656     1666      +10     
==========================================
+ Hits        11735    11761      +26     
- Misses        149      152       +3     
- Partials      357      361       +4

Impacted Files	Coverage Δ
components/tree/nz-tree-node.component.ts	95.3% <92.1%> (-1%)	⬇️
components/tree/nz-tree.component.ts	95.12% <94.44%> (-3.36%)	⬇️
components/tree/nz-tree.service.ts	94.07% <96.29%> (+0.39%)	⬆️

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