BaseTools: Report Error if use SET in Dsc

BaseTools: Report Error if use SET in Dsc

Build tool do not support SET syntax in DSC.
If the SET statement is used in DSC, build tool just ignore it.
That behavior confused some users that
they think SET statement works in DSC like in FDF.
To avoid such confusion, build tool report ERROR
if there is "SET" statement in Dsc file.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Reviewed-by: Cc: Liming Gao <liming.gao@intel.com>