Fix for case where a compound state has a transition to it self.

[knsv]

📑 Summary

Fix for case where a compound state has a transition to it self.

Resolves #3089

📏 Design Decisions

In order to create an edge from a cluster to itself, a fake node is created from which the cluster can link to. This node is not visible but consists only of the (edge) label

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added unit/e2e tests (if appropriate)
• 🔖 targeted develop branch

[github-actions]

🌀 Tests overview by Testomatio

Found 346 cypress tests in 24 files

✔️ Added 1 test

+ State diagram: v2 A compound state should be able to link to itself

📎 List all suites (25)

• Configuration (15 tests) cypress/integration/other/configuration.spec.js
• Interaction (28 tests) cypress/integration/other/interaction.spec.js
• Rerendering (2 tests) cypress/integration/other/rerender.spec.js
• Sequencediagram (3 tests) cypress/integration/other/webpackUsage.spec.js
• XSS (17 tests) cypress/integration/other/xss.spec.js
• Git Graph diagram (9 tests) cypress/integration/rendering/appli.spec.js
• Class diagram V2 (22 tests) cypress/integration/rendering/classDiagram-v2.spec.js
• Class diagram (38 tests) cypress/integration/rendering/classDiagram.spec.js
• Configuration and directives - nodes should be light blue (9 tests) cypress/integration/rendering/conf-and-directives.spec.js
• State diagram (57 tests) cypress/integration/rendering/current.spec.js
• Flowchart (39 tests) cypress/integration/rendering/debug.spec.js
• Entity Relationship Diagram (15 tests) cypress/integration/rendering/erDiagram.spec.js
• Flowchart v2 (38 tests) cypress/integration/rendering/flowchart-v2.spec.js
• Graph (46 tests) cypress/integration/rendering/flowchart.spec.js
• Gantt diagram (10 tests) cypress/integration/rendering/gantt.spec.js
• Git Graph diagram (9 tests) cypress/integration/rendering/gitGraph.spec.js
• Sequencediagram (3 tests) cypress/integration/rendering/info.spec.js
• User journey diagram (4 tests) cypress/integration/rendering/journey.spec.js
• Pie Chart (15 tests) cypress/integration/rendering/pie.spec.js
• Requirement diagram (2 tests) cypress/integration/rendering/requirement.spec.js
• Sequence diagram (44 tests) cypress/integration/rendering/sequencediagram.spec.js
• State diagram (57 tests) cypress/integration/rendering/stateDiagram-v2.spec.js
• State diagram (57 tests) cypress/integration/rendering/stateDiagram.spec.js
• themeCSS balancing, it (2 tests) cypress/integration/rendering/theme.spec.js
• Pie Chart (15 tests) cypress/integration/rendering/theme.spec.js