Refactor `iox_LogLevel` to be consistent with c binding enum names

## Brief feature description

Refactor the `iox_LogLevel` in `iceoryx_binding_c/include/iceoryx_binding_c/log.h` so that it follows the unwritten but consistent naming conventions of enums inside the c binding.
1. enum name is identical to the c++ enum class name with an `iox_` prefix
2. enum values have the c++ enum class name as a prefix.

This would lead to:
```cxx
enum iox_LogLevel {
LogLevel_Off,
LogLevel_Trace,
//....
}
```

without the `iceoryx_` prefix

Start with iceoryx_binding_c/include/iceoryx_binding_c/log.h and compare its iox_LogLevel declaration with the corresponding C++ enum class. Update the enum and value names to follow the stated binding convention, then verify references to the old names across the C binding. Done means the declaration and its uses consistently use the new names.

Written by the indexing model from the issue text.