fix(module:code-editor): load Monaco only once

[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

What kind of change does this PR introduce?

[x] Bugfix

What is the current behavior?

We should load Monaco only once, it even has a warning within its source code (see the screenshot). This applies to apps that are bootstrapped and destroyed multiple times.

What is the new behavior?

Monaco is ensured to be loaded only once.

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 #7033 (f074cc7) into master (b18c050) will decrease coverage by 0.04%.
The diff coverage is 23.80%.

@@            Coverage Diff             @@
##           master    #7033      +/-   ##
==========================================
- Coverage   89.52%   89.48%   -0.05%     
==========================================
  Files         489      488       -1     
  Lines       15768    15772       +4     
  Branches     2573     2572       -1     
==========================================
- Hits        14117    14113       -4     
- Misses       1011     1018       +7     
- Partials      640      641       +1     

Impacted Files	Coverage Δ
components/code-editor/code-editor.service.ts	18.98% <23.80%> (+0.67%)	⬆️
components/tabs/tab-nav-bar.component.ts	82.26% <0.00%> (-0.71%)	⬇️
components/code-editor/typings.ts

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[wzhudev]

LGTM. Thanks!