Determines the common path from a set of paths, using an optional separator, which defaults to the OS default separator.

  import { common } from "https://deno.land/std/path/mod.ts";
  const p = common([
    "./deno/std/path/mod.ts",
    "./deno/std/fs/mod.ts",
  ]);
  console.log(p); // "./deno/std/"