C++ SDK should enforce client to use cxx 17 standard

[pmoulon]

Describe the bug

Using the C++ SDK in the c++ project

Compiler saying:

 error: ‘byte’ is not a member of ‘std’

See here byte required c++ 17 to be activated, not sure the rerun-sdk is enforcing the client to have this cxx standard enforced https://en.cppreference.com/w/cpp/types/byte

Rerun version 0.19

Additional context Issue first discovered here https://github.com/openMVG/openMVG/issues/2368

[Wumpf]

Status quo is that we're setting the property for the rerun target itself here https://github.com/rerun-io/rerun/blob/main/rerun_cpp/CMakeLists.txt#L30 and document that this is something that needs to be done for anyone using Rerun https://rerun.io/docs/getting-started/quick-start/cpp#using-rerun-with-cmake

I think we need to instead use target_compile_features with PUBLIC to make it possible to "infect" any target using Rerun. We need to test though if a user then can still use C++20! If that overrides it, we need to keep things as they are.

https://cmake.org/cmake/help/latest/manual/cmake-compile-features.7.html#requiring-language-standards says

For example, if C++ 11 features are used extensively in a project's header files, then clients must use a compiler mode that is no less than C++ 11.

so this should be doing what we want

[pmoulon]

Thank you @Wumpf for the feedback and details!