feat(std/path): Add fromFileUrl() (#4993)

Fix: URL constructor accepts a URL object which is not a base

std/path/posix.ts

@@ -421,3 +421,14 @@ export function parse(path: string): ParsedPath {
 
   return ret;
 }
+
+/** Converts a file URL to a path string.
+ *
+ *      fromFileUrl("file:///home/foo"); // "/home/foo"
+ *
+ * Note that non-file URLs are treated as file URLs and irrelevant components
+ * are ignored.
+ */
+export function fromFileUrl(url: string | URL): string {
+  return new URL(url).pathname;
+}