FPGATrackSim: implement second stage algorithm and extension tool

This is a component of the "second stage" changes in !74968 (closed), to add support for running an additional extrapolation algorithm after the first track-finding and fitting pass. This commit just contains the new SecondStageAlg itself, the interface for the new "track extension" tool, and one implementation of the TrackExtensionTool, the "window extension" method.

It doesn't include any Python configuration changes or code necessary to make this work-- that wil be added in a subsequent MR. There were a few small changes I had to make to the FPGATrackSimTrack object and the FPGATrackSimMappingSvc interface though to get it to build, although I did comment out one thing in the window extension tool (the magnetic field correction) for now as getting that to work would have been more involved.

Tagging @jahreda for review.