Adding Github Workflow for visual UI integration tests

[tkilias]

Steps:

• Add a new slow test workflow call to the merge-gate.yml
  • Similar to the Ordinary Tests

 visual-itests:
    name: Visual UI Tests
    needs: [ run-slow-tests ]
    uses: ./.github/workflows/tests-visual-ui-integration.yml
    permissions:
      contents: read

• Create .github/workflows/tests-visual-ui-integration.yml similar to https://github.com/exasol/notebook-connector/blob/main/.github/workflows/tests-ordinary-integration.yml
  • However, we need to add the installation of playwright, see developer guide
  • We also need to add the upload of the actual produced screenshots of the tests, if they are not equal to the expected ones
    • see https://solara.dev/documentation/advanced/howto/testing#continuous-integration-recommendations
  • And, we need to point the pytest command to the directory test/ui