Add missing call for C++/Rust API: `--ensure-one-backedge`

[NlightNFotis]

Description

Add support for the goto-instrument option --ensure-one-backedge in the C++/Rust API.

The end result should facilitate an API interaction similar to what you can achieve with the following binary invocation: goto-instrument --ensure-one-backedge-per-target b_harness.out b_harness.out

Context

[This is to track items outlined in #7042 that are missing to make the C++ and Rust API more useful]