Small problems with the IO functions

[developedby]

Reproducing the behavior

I'm writing a guide on how to add IO through dlls in Bend and noticed some problems with run.c and hvm.h.

• hvm.h doesn't expose the inject_ functions. This is useful for returning lists and strings like we do in run.c.
• The definition of struct Str is outdated in hvm.h. It has a fixed size of 256 instead of the new dynamically sized array.
• inject_cons and inject_nil should be called inject_list_cons and inject_list_nil to avoid confusion with String/Cons and String/Nil.

And I also make 2 suggested additions.

inject_list that takes an array of elements and function pointer of how to encode them to HVM. It then calls inject_cons and inject_nil to properly build the list.
inject_string to convert Str to bend strings.

System Settings

HVM: v2.0.21

Additional context

No response