io.lines() equivalent for better iteration over files

[mxruben]

Hello, I am currently looking to write some tools with lune that deal with very large files. The only option for opening files is to read the entire thing into a string in memory. This works fine for smaller files, but when the file is gigabytes large (10 GB in my case), it becomes a real issue. If the fs library could open a file pointer and had something like vanilla lua's io.lines for iteration, it would solve the cases where reading an entire file into a string isn't feasible.

[CleverSource]

I wrote an implementation for this here. I can make a PR if the design for this is improved or we can discuss.

I have a use case that makes this useful. @filiptibell opinions?

[CompeyDev]

Hey! As a part of #211, I implemented a basic async stream system for the new process.create API. Can we abstract the stream implementation into the lune-utils crate and extend it for this sort of chunked reads of files?

That way, we can expand more built-ins with streaming functionality relatively easily.

[CleverSource]

Sounds good to me. I'll update my changes when possible and create a PR when it's ready.