Deno.copyFile
Copies the contents and permissions of one file to another specified path, by default creating a new file if needed, else overwriting. Fails if target path is a directory or is unwritable.
await Deno.copyFile("from.txt", "to.txt");
Requires allow-read permission on fromPath.
Requires allow-write permission on toPath.
function copyFile(fromPath: string | URL, toPath: string | URL): Promise<void>;