Add integration tests for the new diagram layout engine

[sbegaudeau]

In sirius-web-sample-application/src/test/java/org/eclipse/sirius/web/sample/tests/integrations/diagrams, add a new class named DiagramLayoutIntegrationTests which should look like this:

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class DiagramLayoutIntegrationTests extends AbstractIntegrationTests {
    @Autowired
    private IDiagramLayoutEngine diagramLayoutEngine;

    @Autowired
    private ISVGDiagramExportService svgDiagramExportService;

    @Test
    @DisplayName("Given a diagram, when the layout is performed, then valid layout data are computed")
    public void givenDiagramWhenLayoutIsPerformedThenValidLayoutDataAreComputed() {
        var diagramLayoutConfiguration = new TestDiagramLayoutConfigurationBuilder().getConfiguration();
        // TestDiagramLayoutConfigurationBuilder to be created, we can start with a basic configuration for now

        var diagramLayoutData = this.diagramLayoutEngine.layout(diagramLayoutConfiguration);

        var builder = new TestDiagramBuilder(); // The existing TestDiagramBuilder and TestDiagramLayoutConfigurationBuilder should be able to produce coherent types of diagrams
        var diagram = Diagram.newDiagram(builder.getDiagram("diagram"))
                .nodes(List.of(builder.getNode("node")))
                .build();
        var layoutedDiagram = Diagram.newDiagram(diagram)
                .layoutData(diagramLayoutData)
                .build();

       // Improve DiagramAssert to ensure that every elements has some layout data (size, position, etc)

       var svg = this.svgDiagramExportService.export(layoutedDiagram);
       // Log the SVG to help us see the end result for example
    }
}