[analyzer] Indicate if a parent state is infeasible

In some cases a parent State is already infeasible, but we recognize
this only if an additonal constraint is added. This patch is the first
of a series to address this issue. In this patch `assumeDual` is changed
to clone the parent State but with an `Infeasible` flag set, and this
infeasible-parent is returned both for the true and false case. Then
when we add a new transition in the exploded graph and the destination
is marked as infeasible, the node will be a sink node.

Related bug:
https://github.com/llvm/llvm-project/issues/50883
Actually, this patch does not solve that bug in the solver, rather with
this patch we can handle the general parent-infeasible cases.

Next step would be to change the State API and require all checkers to
use the `assume*Dual` API and deprecate the simple `assume` calls.

Hopefully, the next patch will introduce `assumeInBoundDual` and will
solve the CRASH we have here:
https://github.com/llvm/llvm-project/issues/54272

Differential Revision: https://reviews.llvm.org/D124674