doxygen: generate a tag file similar to how other Trilinos packages do

[romintomasetti]

I seems that kokkos-kernels does not produce a Doxygen tag file for now. This means other packages cannot nicely reference kokkos-kernels functionalities:

kokkos-kernels/docs/Doxyfile.in

Line 2287 in 38132f3

GENERATE_TAGFILE =

To enable a kokkos-kernels tag file to be available at https://docs.trilinos.org/dev/packages/common/tag_files, I would propose that docs/Doxyfile.in is simply updated to:

 GENERATE_TAGFILE       = ../../common/tag_files/kokkos-kernels.tag

@cwpearson What do you think ? Thanks!