[C] adding nodiscard for CoSimIO_Info

[philbucher]

I found a way to emulate nodiscard in C :) (with GCC and clang)
Apparently it will be added in C23: https://en.cppreference.com/w/c/language/attributes/nodiscard

this is how the warning message looks like:

home/philipp/software/CoSimIO/tests/integration_tutorials/c/export_mesh.c:87:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
    CoSimIO_CreateInfo();

I would say this is better than manually keeping track of the CoSimIO_Info, what do you think @pooyan-dadvand ?

Changelog:

- creating CO_SIM_IO_NODISCARD to warn when memory is leaked from CoSimIO_Info

[philbucher]

now seems to work fine :)

[pooyan-dadvand]

A good hint for developers!