DataGrid: unskip demo tests

[anna-shakhova]

No description provided.

[Copilot]

Pull request overview

This PR unskips two previously skipped DataGrid demo tests: RemoteGrouping and SignalRService. The PR updates test skip lists, improves the RemoteGrouping test implementation with better selectors and screenshot naming, modifies the SignalRService jQuery demo to wrap cell template content in wrapper divs, and changes the RemoteGrouping jQuery demo to use a different theme stylesheet.

Changes:

• Removes 'RemoteGrouping' from skipped tests in visual test matrix across all frameworks (jQuery, Angular, React, Vue)
• Removes 'SignalRService' from skipped tests configuration for Angular, React, and Vue
• Updates RemoteGrouping test with improved selectors, adds initial screenshot, and renames screenshot files for clarity
• Modifies SignalRService jQuery implementation to wrap cell template content in wrapper divs before appending to container
• Changes RemoteGrouping jQuery demo from dx.light.css to dx.fluent.blue.light.css theme

Reviewed changes

Copilot reviewed 4 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
apps/demos/utils/visual-tests/matrix-test-helper.ts	Removes 'RemoteGrouping' from SKIPPED_TESTS for all frameworks (jQuery, Angular, React, Vue)
apps/demos/testing/skipped-tests.js	Removes 'SignalRService' from skipped tests for Angular, React, and Vue frameworks
apps/demos/testing/widgets/datagrid/RemoteGrouping.test.ts	Improves test with initial screenshot, better selector using .dx-datagrid-expand, and more descriptive screenshot filenames
apps/demos/Demos/DataGrid/SignalRService/jQuery/index.js	Wraps cell template content in wrapper divs for both price and change columns to match intended DOM structure
apps/demos/Demos/DataGrid/RemoteGrouping/jQuery/index.html	Changes theme stylesheet from dx.light.css to dx.fluent.blue.light.css