Moved logic back into VsCommandTarget

Moved the R# logic back into the VsCommandTarget.  Keys like Esc and
Back never actually go through the KeyProcessor in normal scenarios but
straight to IOleCommandTarget.  Hence at this time we must have R#
special case logic at this level.  Very unfortunate.  Trying to find a
better way to do this but for now puttnig it back here.
Fixed the failing unit tests

The VsKeyProcessorSimulation still wasn't entirely accurate.  When a key
down event is translated to an executed IOleCommandTarget event it
wasn't running the key up events.  This does not reflect reality.  The
OLE processing is done on key down only and is not a part of key up.
Changed it to reflect key up semantics

Also changed the R# KeyProcessor to respect discarded KeyInput values.
Unit tests are passing again