Support explicit resource management

[arcanis]

We have quite a few places in Yarn where we manually track the lifetime of wasm-backed data structures (for example here). It'd be nice if we could use the new using syntax (whose support just got merged in TypeScript).

Refs:

• https://babeljs.io/docs/babel-plugin-proposal-explicit-resource-management
• https://github.com/tc39/proposal-explicit-resource-management
• ECMAScript Explicit Resource Management & using Declarations microsoft/TypeScript#52955

[evanw]

Yes. I'm aware and I'm already working on it. Support for the syntax has already been shipped, and I plan to ship support for syntax lowering soon.