[IDEA] More integration tests for Blazor renderer

[Specter-13]

It would be nice to have more integration test for Blazor renderer.
Create some structure for tests, specify correct test-cases.

• tests for each basic layout
• tests for groupbox and border group layouts

[Brano5]

/cib

[PTKu]

Branch 47-_IDEA_More_integration_tests_for_Blazor_renderer created!