feat: neorocksTest Nix helper

[mrcjkb]

No description provided.

[mrcjkb]

For some reason it' doesn't seem to be picking up the lua_interpreter = "neolua" config - although this works just fine in the integration test that uses nix profile install...

[mrcjkb]

🤔 when I copy the generated $LUAROCKS_CONFIG, I can reproduce the behaviour in which it does not use the neolua interpreter locally.
If I comment out the rocks_trees (causing luarocks to download the dependencies), it uses neolua correctly.

[mrcjkb]

The issue seems to be that .busted_wrapped has a call to luajit hardcoded, and luarocks can't change that. Normally, it would change it to use the lua_interpreter.