Bump engines.node to >=10.13.0 and modernize the loader runner:

- Replace `arguments`/`Array.prototype.slice.call` and `.apply(null, arguments)`
  with rest parameters and spread calls across `runSyncOrAsync`,
  `iterateNormalLoaders`, `iteratePitchingLoaders`, and `processResource`.
- Convert the normal/pitching iteration from recursion to iterative while
  loops so chains of already-executed or pitch-less loaders no longer grow
  the call stack and no longer allocate closures per skipped loader.
- Add `escapeHash`, a short-circuiting `#`-escape helper, so the `request`
  and `resource` getters skip the regex scan when the input contains no `#`.
- Replace `.slice().map().concat().join("!")` request composition with a
  single `joinRequests` loop (and a dedicated small loop for
  `previousRequest`), avoiding the intermediate arrays.
- Destructure the object-form `request` assignment, collapse the
  `null`/`undefined` options branch, and clean up the getters with arrow
  helpers and `.slice()` for dependency getters.
- In `loadLoader.js`, drop the legacy `process.nextTick` EMFILE fallback
  and use `setImmediate(loadLoader, loader, callback)` directly, and
  remove the obsolete eslint-disable for `pathToFileURL`.
- Drop the `Error.captureStackTrace` shim in `LoaderLoadingError` since
  Node 10+ captures stack traces correctly for subclassed Errors.