Review Mozilla 1970183: Add a llama.cpp backend

🔍 Bugzilla Audit

Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1970183

Description

It adds dom/webidl/LlamaRunner.webidl, but the bindings reference a header in the directory we disable.

We will need to disable this for starters.

---