upd: improve Shape_Op resilience
Context
Improve Shape operator resilience. Force the output type to int64.
Detailed major modifications
- add: assertions on start and end attributes
- add: override of Shape_Op::setDataType always setting output type to DataType::Int64
- use shape copy from vector insead of creating a Tensor in Shape_Op::forwardDims()
- upd: 'Test_ShapeImpl.cpp'