ref: Modernize and streamline iitm/ritm for our usecase

[Luca Forstner (lforst)]

• Changed identifiers on various things for import-in-the-middle so that we are less likely to conflict with the real one: Renamed URL marker from ?iitm to ?braintrust_iitm and also renamed global state identifier.

• Made it so that module patching is 100% explicit, meaning iitm/ritm only wraps modules passed to new Hook([...]). We removed the include, exclude, or shouldInclude which make sense for the public package but not our forchetta.

• Changes some abysmal looking 2004-era-looking-ass to normal classes. Say what you will about classes but they are better than Hook.prototype.unhook = function (this: HookInstance): void {

• We now have two ways to run IITM: The older way with module.register() loader is async/off-thread, and the newer module.registerHooks() is sync/in-process. Both need to store the next resolver int he pipeline so they can correctly resolve export * from ... while building wrapper modules. Previously they both shared one cachedResolve variable - now we split the two into cachedAsyncResolve and cachedSyncResolve so the async path never accidentally calls a sync resolver, and vice versa.

• Made it so that when a package re-exports another CommonJS package from nested node_modules we make sure we correctly patch it by using process.cwd() instead of import.meta.url.

• Tests for everything