refactor: new module graph used for no check

[kitsonk]

This PR is part of #7225 and introduces a new module graph that is more fit for purpose for how Deno handles code and dependencies. Because the refactor will take a while to do and we don't want huge PR, the first step is to utilise the module graph to do the --no-check transpile only.

This makes the whole API far more easier to understand what is going on, and makes it overall more maintainable. A simplified version of doing the transpile now looks like this:

let handler =
  Rc::new(RefCell::new(FetchHandler::new(&flags, &permissions)?));
let mut builder = GraphBuilder::new(handler, maybe_import_map);
builder.insert(&module_specifier).await?;
let mut graph = builder.get_graph();

let maybe_config = get_maybe_config();

let (stats, maybe_ignored_options) =
  graph.transpile(TranspileOptions {
    debug: flags.log_level == Some(log::Level::Debug),
    maybe_config,
  })?;

debug!("{}", stats);
if let Some(ignored_options) = maybe_ignored_options {
  println!("Some compiler options were ignored:\n  {}", ignored_options);
}

The module graph becomes the "controller" which orchestrates fetching modules, doing dependency analysis, and reading and writing to the disk cache.

Things to do on this PR:

• Moar tests
• Remove unused code

[ry]

Does this mean there will be two module graphs? This patch is a rather large net addition of code, so it needs to be carefully considered before landing.

[kitsonk]

Yes, two module graph for a small period of time as we transition, as a total refactor was considered a bad idea. I tried other ways of swallowing the elephant, and this was the best I could come up with. Expand and then contract...

At the end of the journey, it will result in thousands of lines of less code.

[kitsonk]

Just to give an idea of the long term roadmap, is something like this:

• tsc.rs should go from ~1700 > ~600
• module_graph.rs would be fully replaced (~970)
• a reduction of ~300-~400 in file_fetcher.rs
• the JavaScript code in tsc should go from ~1800 down to ~430

I suspect I need to add about ~500 lines to the new graph.rs to facilitate the rest of it. So in the end a savings of about 3k of code.

[bartlomieju]

LGTM! Just a few minor comments. I understand that this is transitive state before complete cleanup so I don't mind additional code for a few days.

[bartlomieju]

Use type alias instead? That way there will be no need for custom Deserialize implementation

[kitsonk]

I've got a custom fmt:Display as well. It is nice to have it all be self contained, IMO.

[kitsonk]

@bartlomieju addressed your feedback, PTAL.

[bartlomieju]

@kitsonk LGTM