Don't use lua-format for output normalisation

[jparoz]

We can probably just use an off-the-shelf Lua parser to parse, and implement some simple renderer of the parsed tree.

This would also be useful in parsing of our actual files, because then we can validate that the contents of lua {...} blocks is at least valid Lua syntax, or validate that it is a valid Lua expression, or even validate that it's a valid Lua expression which only depends on things it's allowed to from the Huck scope! As well as validating foreign export paths.