The InputStateMachineEngine was incorrectly not returning to the ground state
  after flushing the last sequence. That means that something like alt+backspace
  would leave us in the Escape state, not the ground state. This makes sure we
  return to ground.

  Fixes #2746.

  Additionally removes the "Parser.UnitTests-common.vcxproj" file, which was
  originally used for a theoretical time when we only open-sourced the parser.
  It's unnecessary now, and we can get rid of it.

  Also includes a small patch to bcz.cmd, to make sure bx works with projects
  with a space in their name.

Co-Authored-By: Dustin L. Howett (MSFT) <duhowett@microsoft.com>

…eturn-to-ground