Chore: Moving VDF to core and some fixes

[tkchouaki]

Besides Moving the VDF functionality from the VDF module to the core one, this PR does the following:

• VDFEngine expects PlanAgent agents, this is true for most simulations but in some cases, as when DRT is used, this is not the case. This case is now handled but generateNetworkEvents needs to be set to true.
• The modes set objects in VDFConfigGroup and VDFEngineConfigGroup were initialized with immutable sets, which causes an exception to be thrown in the call to .clear() in the string setters. They have been replaced to mutable ones.
• The VDF and VDFEngine config groups are now detected automatically in the EqasimConfigurator and activated
• An AdaptConfigForVDF class is added, does the typical addition of the VDF and VDFEngine config groups
• The VDF functionality is now tested

Closes #236.