Rename the alpaka namespace alpaka::concepts to alpaka::interface because it can be easily mixed up with C++20 concepts. But alpaka::concepts functionality does not implement C++20 with C++17. Instead it allows to implement a type hierarchy allows to check for it. That's a similar concept like Java interfaces. Therefore we name it interface now.
Rename the alpaka namespace
alpaka::concepts
toalpaka::interface
because it can be easily mixed up with C++20 concepts. Butalpaka::concepts
functionality does not implement C++20 with C++17. Instead it allows to implement a type hierarchy allows to check for it. That's a similar concept like Java interfaces. Therefore we name it interface now.