Changes

Bug 580187 - [Designer, releng] Create a minimal feature/RCP for code generation

- Remove UI dependency (org.eclipse.ui) in many MANIFEST.MF
	=> Activator extends class Plugin instead of AbstractUIPlugin
- Cleanup of non-required dependencies in many MANIFEST.MF files
- Remove upper restriction on css plugin (compatibility with 2023-12)
- Split oepr.ros2.preferences plugin in UI and non-UI part
	=> add additional plugin to feature and to pom
	=> TODO: StartupCheck is triggered via UI plugin. This needs some re-considerations
- Don't defined MARTE URI, since already defined in SW Designer

Change-Id: I281d3d55d0190b3299c5f430d41a42a7a6b27c02
Signed-off-by: aradermache <ansgar.radermacher@cea.fr>