Handle vary by segment variant-entires

[nielslyngsoe]

Ensures variant data that varies by segment and not by culture are handled as well and gets stored as a variant-Entry with culture, despite the cross existance of the value.

[Copilot]

Pull Request Overview

This PR fixes handling of variant data that varies by segment but not by culture in Umbraco's content management system. The changes ensure that segment-specific variant entries are properly stored with culture information even when the property doesn't vary by culture.

• Improves variant name display logic to handle empty/whitespace variant names gracefully
• Adds logic to ensure segment variants are created for all cultures when properties vary by segment but not culture
• Refactors data processing to handle segment-only variants correctly

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
workspace-split-view-variant-selector.element.ts	Improves variant name display by checking for empty/whitespace variant names
content-detail-workspace-base.ts	Adds logic to create segment variants across all cultures when needed
element-data-manager.ts	Refactors data processing and improves segment filtering logic
content-data-manager.ts	Adds clarifying comment for segment handling