Introduce `resultify` function

Summary of Changes:

• introduce new helper function resultify

Detailed Changes:

resultify is a helper function akin to Node.js's utils.promisify.
It modifies the return type of any given function, synchronous or asynchronous, to Result.

Examples:

import { Result, Err, resultify } from 'type-safe-errors';

class FetchFailedError extends Error {
  name = "FetchFailedError" as const;
}

async function fetchDataOrErrorResult () {
  try {
    const res = await fetchRemoteData();
    return res.data;
  } catch (err) {
    console.log(err);
    return Err.of(new FetchFailedError());
  }
};

const fetchRemoteDataAsResult = resultify(fetchDataOrErrorResult);
fetchRemoteDataAsResult()
  .map(data => data)
  .mapErr(FetchFailedError, (err) => console.log(err));