lua: Extract to zed-extensions/lua repository (#26250)

This PR extracts the Lua extension to the
[zed-extensions/lua](https://github.com/zed-extensions/lua) repository.

Release Notes:

- N/A

Cargo.toml

@@ -173,7 +173,6 @@ members = [
     "extensions/glsl",
     "extensions/haskell",
     "extensions/html",
-    "extensions/lua",
     "extensions/perplexity",
     "extensions/proto",
     "extensions/purescript",