Separate arch specific code to directories

[pjanevskiTT]

Separate arch specific code into separate directories. This way we achieve two things

• Avoid conditional compilation (Remove conditional compilation #51) -> we can have build target for each arch
• Code organization looks much better

For example, for something like https://github.com/tenstorrent/tt-umd/blob/main/device/driver_atomics.h, we should have something like

arch
|----- x86
|       |------ driver_atomics.hpp
|
|----- arm
|       |------ driver_atomics.hpp

Maybe driver atomics file is not the right granularity to do this, maybe we need to do it in smaller/bigger chunks, but that should be investigated through this issue as well.

[pjanevskiTT]

We already had one PR closed on this because it adds complexity, I won't close this because it would be good to have this sometime in the future, but it is really low prirority at the moment