gui: add missing stubs getDescriptor & removeSelectedByType
gui: add missing stubs getDescriptor & removeSelectedByType

Signed-off-by: Matt Liberty <44ef1ce0ef6935daf739a0795dad249ba5322e97@eng.ucsd.edu>

QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD