[CUDA][HIP] Fix device template variables

Currently clang does not emit device template variables
instantiated only in host functions, however, nvcc is
able to do that:

https://godbolt.org/z/fneEfferY

This patch fixes this issue by refactoring and extending
the existing mechanism for emitting static device
var ODR-used by host only. Basically clang records
device variables ODR-used by host code and force
them to be emitted in device compilation. The existing
mechanism makes sure these device variables ODR-used
by host code are added to llvm.compiler-used, therefore
they are guaranteed not to be deleted.

It also fixes non-ODR-use of static device variable by host code
causing static device variable to be emitted and registered,
which should not.

Reviewed by: Artem Belevich

Differential Revision: https://reviews.llvm.org/D102237