High-level language bindings to libgpiod

Bindings provide a more straightforward interface to the core, low-level C library. Object-oriented bindings for C++, GLib, python3 and Rust are provided as part of the project. They can be enabled by passing --enable-bindings-cxx, --enable-bindings-glib, --enable-bindings-python and --enable-bindings-rust arguments to configure respectively.