* Prepend underscores to private modules
* Remove collectUint8Arrays() It would be a misuse of Deno.iter()'s result.
* Move std/_util/async.ts to std/async
* Move std/util/sha*.ts to std/hash
Adds JSDoc to module, improves the typing of the return type, uses
iteration instead of Array forEach, uses the dotall support in Regular
Expression which is now supported in JavaScript, uses destructuring and
nullish coalescing where appropriate.