[Fix] update backend cuda

Context

This MR is dedicated to handle two updates:

• getAvailableImplSpecs now returns std::vector<ImplSpec> instead of std::set<ImplSpec>.
• Add supports only 2 inputs

Modified files

• Test_AddImpl.cpp, Update Add unit tests to handle only 2 inputs;
• All Operators Impls headers, update getAvailableImplSpecs returned type;

TODO

• getAvailableImplSpecs Fix
• Add tests Fix

include/aidge/backend/cuda/operator/AddImpl.hpp

@@ -36,7 +36,7 @@ public:
         return std::make_unique<AddImpl_cuda>(op);
     }
 
-    virtual std::set<ImplSpec> getAvailableImplSpecs() const override {
+    virtual std::vector<ImplSpec> getAvailableImplSpecs() const override {
         return {
             {DataType::Float64},
             {DataType::Float32},