ActsGeometry+ActsPriVtxFinder: Fix compilation error with clang.

In ActsExtrapolationTool and ActsAdaptiveMultiPriVtxFinderTool, we need to ensure that ReferenceWrapperAnyCompat gets included early. Otherwise, we were seeing failures in the clang build due to the specialization of is_constructable defined in that file getting implicitly instantiated earlier.

Since ReferenceWrapperAnyCompat.hpp is in detail, do this instead by including Propagator.hpp.