Development Eclipse EMF Parsley

Update to a new Eclipse release and Xtext release

Update the Oomph file devtools/org.eclipse.emf.parsley.oomph/EMFParsley.setup: add another target platform node, e.g., "2024-03" (copying the latest existing one), for the current Eclipse release, in "Modular Target" both for "RCP" and "RAP".
- In that new node for the target platform update the URL of the Eclipse releases and the Orbit update site (e.g., https://download.eclipse.org/tools/orbit/simrel/orbit-aggregation/2024-03).
- Change the default value of eclipse.target.platform to the new target platform
Run the Oomph workflow (when run from Eclipse already Oomphed, change the Target Plarform to the latest one).

Both the simrel.target and simrel-rap.target in org.eclipse.emf.parsley.targetplatform with the URL of the Eclipse releases and the Orbit update site (e.g., https://download.eclipse.org/tools/orbit/simrel/orbit-aggregation/2024-03).

Update the property <eclipse-version>2023-12</eclipse-version>.