adding atomic support with atomix

Created by: leios

After some discussions on #282, we decided to use Atomix for atomic support in KA.

A few quick questions:

1. Because Base (and CUDA) both have an @atomic macro, we need to specify that we are using the Atomix.@atomic macro in code that needs atomic operations. Should we overdub any @atomic macros in KA to specifically use Atomix?
2. Should we add in the tests from #282?
3. What about atomic primitives like atomic_add!(...), and atomic_sub!(...) from #282? These come from either CUDA or Core.Intrinsics. Maybe it's a good idea to use Atomix on top of #282? I don't know how many people will use the primitives over the macro, to be honest.

Note, this should not be merged until https://github.com/JuliaRegistries/General/pull/61002 is automerged.