1) Add DebugMask.h that defines the GUID and Protocol used by the "err" EFI Shell command to get/set the global mask and get/set the module scoped masks
2) Add DxeDebugPrintErrorLevelLib that provide an implementation of the DebugPrintErrorLevbel library classes that uses the GUID and Protocol defined in DebugMask.h to "err" EFI Shell compatibility.
3) Add default mapping for the DebugPrintErrirLevelLib to the DSC file for this package.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11366 6f19259b-4bc3-4df7-8a09-765794883524