Rewrite require and luaurc in lune-std

[FlowGnarly]

Highlights of this PR

• doesn't mutably borrow the app container for the entire require process (Fixes Creating a new DataModel and setting it as a global called game errors #236, Fixes Require in metamethod causes a panic #262)
• allows custom libraries that impl the StandardLibrary trait to be added to the require envrionment (Fixes Customizing globals without having to fork lune [lune-std] #197)

   context::RequireContext::inject_std(lua, "custom", CustomStandardLibrary::Timer)?;

   local timer = require("@custom/timer")

• the luaurc parser has better error handling and doesnt fail silently when it fails to parse a .luaurc file (Fixes unable to find .luaurc if .luaurc contains invalid JSON syntax #210)

  Failed to parse /path/to/.luaurc
  ParserError: trailing comma at line 16 column 1
  [Stack Begin]
          Script '[C]'
          Script '__mlua_async_poll', Line 4
          Script 'REPL', Line 1
  [Stack End]

API Changes

for the existing crates that use lune-std nothing has to be changed, since this pr only changes the internal code and adds 2 new items which are totally optional and can be accessed by other crates, which are:

pub trait StandardLibrary
where
    Self: Debug,
{
    fn name(&self) -> &'static str;
    fn module<'lua>(&self, lua: &'lua Lua) -> LuaResult<LuaMultiValue<'lua>>;
}

pub struct RequireContext {}

impl RequireContext {
    pub fn inject_std(
        lua: &Lua,
        alias: &'static str,
        std: impl StandardLibrary + 'static,
    ) -> Result<(), RequireError>;
}

[filiptibell]

Thank you for the PR! I have not yet made comments on any specific files because I wanted to bring a few general points up. First, the positives:

• The improvements in error handling and the more strongly typed errors are great. I believe this to be the main highlight of this PR.
• The new library trait is a good change for flexbility and I hope we can also use it in the future for package management or something similar.

And then, a couple negatives:

• There are areas where this new implementation introduces TOCTOU race conditions, due to the heavy usage of fs::try_exists. It is very important that if a file read succeeds, we use the contents of the file at that specific moment in time.
• Rewriting LuauRc fully and removing every field but the aliases one may have been a step too far. It would be nice if Lune could help the user in case they have an invalid config and tell them what is wrong with their fields other than just the aliases. We just needed better error propagation.

Finally, some nitpicks. Feel free to ignore them and wait for me to comment on the specific files and locations if you wish:

• We can use the path utils from lune_utils::path instead of re-implementing new versions in lune-std.
• In many cases the new error propagation, which is great, introduces allocation when not necessary. Try to use ok_or_else instead of ok_or when creating the error needs allocation.

[FlowGnarly]

Hey thanks for the feedback! I really appreciate it

There are areas where this new implementation introduces TOCTOU race conditions, due to the heavy usage of fs::try_exists. It is very important that if a file read succeeds, we use the contents of the file at that specific moment in time.

Ive changed quite alot of code to get around this, it should be good now 😅

Rewriting LuauRc fully and removing every field but the aliases one may have been a step too far. It would be nice if Lune could help the user in case they have an invalid config and tell them what is wrong with their fields other than just the aliases. We just needed better error propagation.

I had no idea why we we're de-serializing all those fields hence I didn't include them in the rewrite, I've bringed back all the fields into the struct so it should be good now (excluding the paths field, because I couldn't find it in any luau rfc, what's that about?)

We can use the path utils from lune_utils::path instead of re-implementing new versions in lune-std.

I didn't know we had all those functions in lune_utils lol, I've removed all the duplicate functions and replaced them with the lune_utils path functions

Try to use ok_or_else instead of ok_or when creating the error needs allocation.

Done!