cleanup include ze_api.h

[bratpiorka]

Description

ze_api.h should be always:

• included from the deps (build/_deps/level-zero-loader-***) for all internal code including tests
• included from the system paths in the examples

Checklist

• Code compiles without errors locally
• All tests pass locally
• CI workflows execute properly

[KFilipek]

If you plan to reorder headers, please, use Coding style guidelines.
As I remember, external headers should be in a separate block. Currently, they are mixed.
E.g. ze_api.h or mutex

[bratpiorka]

If you plan to reorder headers, please, use Coding style guidelines. As I remember, external headers should be in a separate block. Currently, they are mixed. E.g. ze_api.h or mutex

We don't have strict coding style rules - we only have what's here: https://github.com/oneapi-src/unified-memory-framework/blob/main/CONTRIBUTING.md#code-style
But regarding the order - I keep the "standard" includes fist (), then UMF interface that is supposed to be installed (<umf/*>) and local includes at the end. In "test/providers/provider_level_zero.cpp" I threat "ze_api.h" as a local header, because it is downloaded by UMF to the _deps folder and I intentionally keep it with the other local files

[kswiecicki]

If you plan to reorder headers, please, use Coding style guidelines. As I remember, external headers should be in a separate block. Currently, they are mixed. E.g. ze_api.h or mutex

From what I see, the ze_api.h header is treated as external in examples, and as internal in umf sources/tests. In case of examples, @bratpiorka mentioned it should come from system paths from the user.