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

[elfenpiff]

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:

enum iox_LogLevel {
  LogLevel_Off,
  LogLevel_Trace,
  //....
}

without the iceoryx_ prefix

[elBoberido]

@MatthiasKillat AFAIK this is only used in Cylone DDS. Probably only Iceoryx_LogLevel_Off. Can you confirm?