Add 2D diffusion operator w/o blending for the P2PlusBubble FE space

generate/generate.py

generate/requirements.txt

operators-diffusion.toml

operators/diffusion/CMakeLists.txt

operators/diffusion/P2PlusBubbleElementwiseDiffusion.cpp

operators/diffusion/P2PlusBubbleElementwiseDiffusion.hpp

...usion_apply_P2PlusBubbleElementwiseDiffusion_macro_2D.cpp

...ratorValues_P2PlusBubbleElementwiseDiffusion_macro_2D.cpp

...usion_apply_P2PlusBubbleElementwiseDiffusion_macro_2D.cpp

...ratorValues_P2PlusBubbleElementwiseDiffusion_macro_2D.cpp

...on_toMatrix_P2PlusBubbleElementwiseDiffusion_macro_2D.cpp