Feature Request: Use system Lua instead of bundling it in the extension

To avoid bloat (shipping multiple versions of Lua *just in case*) and version mismatches (not catching up to the latest version Lua *as it is currently the case*), use the system installed Lua binaries (from `PATH` or from a user provided path) like how the other extensions do it. The formatter should ideally also be provided separately.

Start by locating how the extension currently bundles and launches Lua binaries, then compare how the other extensions discover system-installed binaries. Define the PATH and user-provided-path behavior, and verify that the formatter can be supplied separately without the extension shipping multiple Lua versions.

Written by the indexing model from the issue text.