Shellpkg: Add support for filenames with spaces.

Shellpkg: Add support for filenames with spaces.

This patch changes the file redirection support to allow for quote delimited filenames that contain spaces and updates the edit command to allow spaces in the filename.  This also properly fails for attempts to redirect to "" (empty quotes).

This was missing from the first portion of the commit.

signed-off-by: jcarsey
reviewed-by: jliu66

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12686 6f19259b-4bc3-4df7-8a09-765794883524