Typeguard-friendly Array#every

[fazouane-marouane]

Fixes # I'm not aware of any issue

This PR tries to address the following. However, it may not play well with mutations.

function is_number(v: unknown): v is number {
  return typeof v === "number";
}

function weird_sum(collection: Array<string | number>) {
  if (collection.every(is_number)) {
    // currently, typescript raises an error here
    const sum: number = collection.reduce((acc, v) => acc + v);
    return sum;
  }
  return 0;
}

weird_sum([5, "abc", 42]);

Please verify that:

• There is an associated issue in the Backlog milestone (required)
• Code is up-to-date with the master branch
• You've successfully run gulp runtests locally
• There are new or updated unit tests validating the change

[typescript-bot]

It looks like you've sent a pull request to update our 'lib' files. These files aren't meant to be edited by hand, as they consist of last-known good states of the compiler and are generated from 'src'. Unless this is necessary, consider closing the pull request and sending a separate PR to update 'src'.

[msftclas]

All CLA requirements met.

[ikokostya]

Duplicate of #38200