function Deno.writeFile
writeFile(): Promise<void>
Write `data` to the given `path`, by default creating a new file if
needed, else overwriting.
```ts
const encoder = new TextEncoder();
const data = encoder.encode("Hello world\n");
await Deno.writeFile("hello1.txt", data); // overwrite "hello1.txt" or create it
await Deno.writeFile("hello2.txt", data, { create: false }); // only works if "hello2.txt" exists
await Deno.writeFile("hello3.txt", data, { mode: 0o777 }); // set permissions on new file
await Deno.writeFile("hello4.txt", data, { append: true }); // add data to the end of the file
```
Requires `allow-write` permission, and `allow-read` if `options.create` is
`false`.
Promise<void>