ShellPkg: fix mv and cp command related issues

1.mv deletes file/directory when trying to move it to non-existing file system.
2.mv causes RSOD in system when trying to move same file at the same location.
3.Refactor mv and cp command with command name passed-in.
remove redundant move status error message when file failed to move across file system.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Tapan Shah <tapandshah@hp.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17129 6f19259b-4bc3-4df7-8a09-765794883524