Update TrackExtensionAlg to run CKF inward

Tomasz Boldrequested to merge
tbold/athena:fit-prototrack-in-extension-alg-at-measurement-surface into main

In this MR the TrackExtension is modified to:

  • obtain track parameters at first measurement's surface
  • start CKF inward from there

Tagging @pibutti @jahreda @sabidi

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