Cherry-pick PR #16618: fix calendar date styles and formatting to 20.1.x

[Copilot]

• Understand the changes from PR fix(calendar): fix date styles and formating #16618 (date styles and formatting fixes)
• Create new file: day-digit.pipe.ts in the correct location for 20.1.x
• Update days-view.component.html to use the dayDigit pipe
• Update days-view.component.ts to import DayDigitPipe
• Update days-view.component.spec.ts with the new test
• Update calendar theme SCSS to add white-space: nowrap
• Update calendar sample files to include formatViews and zh-CN locale
• Build and test the changes (build successful, lint passed)
• Run code review (passed with no comments)
• Run security checks (no issues detected)
• Revert unintended package.json change

Summary

Successfully cherry-picked all changes from PR #16618 to the 20.1.x branch. The changes fix date styles and formatting issues in the Calendar component, particularly for locales like zh-CN that include non-numeric characters in date formatting (e.g., "25日"). All files have been adapted to the 20.1.x directory structure, and the implementation maintains consistency with the original PR. Reverted the unintended addition of karma-jasmine-spec-tags to package.json.

Original prompt

Cherry-pick the changes from the merged pull request #16618 (fix(calendar): fix date styles and formatting) into the 20.1.x branch. Ensure all fixes for date styles and formatting in the Calendar component are accurately applied to maintain consistency across versions.

This pull request was created as a result of the following prompt from Copilot chat.

Cherry-pick the changes from the merged pull request #16618 (fix(calendar): fix date styles and formatting) into the 20.1.x branch. Ensure all fixes for date styles and formatting in the Calendar component are accurately applied to maintain consistency across versions.

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[desig9stein]

@copilot revert the change you made in the package.json file

[Copilot]

@copilot revert the change you made in the package.json file

Reverted the karma-jasmine-spec-tags change in commit 02837b7.