Testable Graph Builder exception fix

[Auriga2]

Prerequisites

• [x] Reviewed the checklist

• [ ] Reviewed feedback from the "Sonar Cloud" bot. Note that you have to wait for the "CI / Unit Tests") to complete first. Failed Unit tests can be debugged by adding the label "verbose logging" to the GitHub PR.

Description of the Change

The exception was throwing if Experimental ->Developer ->Testable Graph Builder was clicked while there's a non empty graph open in constellation. Fixed it by opening the Testable Graph in a new analytic graph rather than just showing a warning message.

Alternate Designs

Could have just shown a warning message, but opening it in a new graph with the same click make it even easier for developers.

Why Should This Be In Core?

Fix exception

Benefits

Open Testable graph with one click

Possible Drawbacks

Verification Process

Select Experimental ->Developer ->Testable Graph Builder without opening any graphs and with any open graphs

Applicable Issues

https://github.com/constellation-app/constellation/issues/2150

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarCloud