Redesign JoinLattice

[fabianbs96]

IDE analyses need to define a JoinLattice over the edge-value domain. This is currently done by defining the IDE-problem as JoinLattice is a base-class of IDETabulationProblem. However, this has a couple of drawbacks:

• Conceptually implementing a JoinLattice should be a trait on the edge-value type, not on the IDEProblem
• Some optimizations are missed, for example AllBottom needs to explicitly store the bottom value
• Most of the composeWith and joinWith functions on EdgeFunctions cannot be properly defaulted

This PR has the following contributions:

• Makes JoinLattice a trait on the edge-value's type. This feature is opt-in and in case it is provided, the old representation is defaulted in terms of the new rep
• Optimize default edge functions (AllBottom, AllTop, EFComposer, ...)
• Implement a new default edge function: ConstantEdgeFunction. Nearly all IDE analyses need this to generate values from zero. To ease constant function handling, EdgeFunctions now have a new virtual member function bool isConstant() that tells whether the output of computeTarget depends on the source edge value.
• The new Join Lattice representation together with the new and improved default edge functions have been implemented for the IDELinearConstantAnalysis as a proof of concept

[MMory]

This is a breaking change, isn't it? Before merging BreakingChanges.md should be updated then.

[MMory]

This is a breaking change, isn't it? Before merging BreakingChanges.md should be updated then.

[fabianbs96]

This should be completely opt-in