Importable env types, take 2

[penalosa]

This adds a namespaced type for importable env, Cloudflare.Env. This can be provided by a user .d.ts file via something like:

declare namespace Cloudflare {
 	interface Env {
 		string: 'hello world';
 		json: { key: 'value' };
 		SECRET: string;
	}
}

This will be generated by wrangler types in the near future

[github-actions]

The generated output of @cloudflare/workers-types matches the snapshot in types/generated-snapshot 🎉

[hoodmane]

Makes sense to me. What was take 1?