support new luajit 2.1 syntax

[max397574]

Luajit recently backported some syntax into version 2.1 which stylua doesn't support yet:
LuaJIT/LuaJIT#1476

Would it be possible to add support for this?

[max397574]

I guess this would also require https://github.com/Kampfkarren/full-moon to support it.

They don't list luajit explicitly as supported. Any idea what's the status of that?