[l10n] Add Chinese (Hong Kong) (zh-HK) locale

[samchiu90]

• I have followed (at least) the PR section of the contributing guide.

Add Traditional Chinese text in Hong Kong (zhHK) locale for date-pickers

[mui-bot]

Localization writing tips ✍️

Seems you are updating localization 🌍 files.

Thank you for contributing to the localization! 🎉 To make your PR perfect, here is a list of elements to check: ✔️

• Verify if the PR title respects the release format. Here are two examples (depending if you update or add a locale file)

  [l10n] Improve Swedish (sv-SE) locale
  [l10n] Add Danish (da-DK) locale

• Update the documentation of supported locales by running yarn l10n
• Verify that you have added an export line in src/locales/index.ts for the new locale.
• Run yarn docs:api which should add your new translation to the list of exported interfaces.
• Clean files with yarn prettier.

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Netlify deploy preview: https://deploy-preview-9468--material-ui-x.netlify.app/

Updated pages

No updates.

These are the results for the performance tests:

Test case	Unit	Min	Max	Median	Mean	σ
Filter 100k rows	ms	502.3	999.7	771.5	732.14	168.48
Sort 100k rows	ms	657	999.7	947.8	897.74	127.07
Select 100k rows	ms	195.1	466.9	258.4	305.24	97.062
Deselect 100k rows	ms	146.6	365.8	215.8	228.2	74.325

Generated by 🚫 dangerJS against dc6e639

[LukasTy]

Thank you for your contribution! 🙏
Have you ran the yarn l10n script on Windows and it generated links with double backslahes (\\) instead of a froward slash (/)? 🤔