New DCE/RPC MDSSVC: make dissect_spotlight() a global function

Change-Id: I5c9dbd59b18eff5dc9cb9476f1883cb9fa9d9c02
New DCE/RPC MDSSVC: add IDL file and generated dissector

Change-Id: I8832c139938e767de71b2cc74ca41208f509e478