Decouple JDT dependencies from org.yakindu.sct.commons and others

[jdicks]

The JDT dependency was added for accessing classpath entries of a java project during simulation and code generation. this is only needed if java based resources, available in the current runtime workspace, have to be accessed.

To avoid the need of JDT in case no java based resources are necessary these dependencies should be decoupled and added just if urgently needed.

you can get a list of all plugins dependent from JDT by searching for
org.eclipse.jdt.core AND org.eclipse.jdt.launching within *.MF

[jdicks]

plugins dependent from jdt:

org.yakindu.sct.commons
org.yakindu.sct.generator.c
org.yakindu.sct.generator.core
org.yakindu.sct.generator.cpp
org.yakindu.sct.generator.csharp
org.yakindu.sct.generator.csharp.test
org.yakindu.sct.generator.genmodel.ui
org.yakindu.sct.generator.java
org.yakindu.sct.generator.java.test
org.yakindu.sct.simulation.core
org.yakindu.sct.simulation.ui
org.yakindu.sct.standalone

see also #676: feature 'org.yakindu.sct-feature' adds jdt dependencies transitively

[andreasmuelder]

This will be fixed via #676