fix(module:code-editor): re-enter the Angular zone only if the value has been changed

[arturovt]

PR Checklist

• 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

[x] Bugfix

What is the current behavior?

Currently, it's running tick() whenever the onDidChangeContent callback is invoked, but there's an if condition which checks if the value has been changed and does nothing if not.

What is the new behavior?

The nz-code-editor will run tick() only if the value has been changed.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #6845 (bd29a21) into master (29d44af) will increase coverage by 0.01%.
The diff coverage is 0.00%.

❗ Current head bd29a21 differs from pull request most recent head f3d06c2. Consider uploading reports for the commit f3d06c2 to get more accurate results

@@            Coverage Diff             @@
##           master    #6845      +/-   ##
==========================================
+ Coverage   89.55%   89.56%   +0.01%     
==========================================
  Files         489      489              
  Lines       15796    15796              
  Branches     2427     2427              
==========================================
+ Hits        14146    14148       +2     
+ Misses       1008     1007       -1     
+ Partials      642      641       -1     

Impacted Files	Coverage Δ
components/code-editor/code-editor.component.ts	14.65% <0.00%> (ø)
components/tabs/tab-nav-bar.component.ts	83.03% <0.00%> (ø)
components/core/util/text-measure.ts	91.30% <0.00%> (+1.73%)	⬆️

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[hsuanxyz]

LGTM