Background LLGuidance

This wraps the crate llguidance and adds ability to compute masks in background thread, as well as exposes additional C APIs.

The build process for this crate creates the following files in target/release:

• libllguidance_bg.a - the static library to be linked into C++
• llguidance.h and llguidance_bg.h - the C header files to be included in C++ code
• llguidance_bg_cpp.h - a C++ single-header wrapper around the C APIs