Drop old compilers from CI

and update compiler version checks in CMake

compiler	minimum	current
Intel	2017	2019
GCC	5	8
Clang	4	7
MSVC	2017	?

Minimum CUDA version for C++14 is 9.0 So use the appropriate CUDA versions for each compiler.

CUDA	GCC	Clang	Intel
9.0	5-6	none	17
9.1	5-6	4	17
9.2	5-7	4-5	17
10.0	5-7	4-6	17-18