Use `sync` variant of file operations

`readFIle` --> `readFileSync`
... and any others

This could be seen as quite a file-heavy module, so i think speed can be a concern. By nature, async operations are slightly slower to process than sync operations (as in awaiting those). Alongside this, I have seen time and time again (and ive just tested this again), that Deno's sync methods are faster than the async variant (about 400% faster when comparing readFile and readFileSync)

So thats why i think it would be a good idea to do this, and there's no loss - maybe even some methods may not even need an `await`