BaseTools: Move CreateAsBuiltInf into AutoGenWorker for parallel
    
    AsBuiltInf can be created during AutoGen phase. Move CreateAsBuiltInf
    into AutoGenWorker to make this step run in parallel.
    
    Signed-off-by: Bob Feng <bob.c.feng@intel.com>
    Cc: Liming Gao <liming.gao@intel.com>
    Cc: Yuwei Chen <yuwei.chen@intel.com>
    Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
    Reviewed-by: Bob Feng <bob.c.feng@intel.com>