Add export for helpers

[Mangatt]

It would be nice to have exports for helpers mentioned in docs. Right now it's something like that:

import nextCloudHelper from 'nextcloud-link/compiled/helper'
const { createOwnCloudFileDetailProperty } = nextCloudHelper

It would be better to have:

import { createOwnCloudFileDetailProperty } from 'nextcloud-link'

or

import { createOwnCloudFileDetailProperty } from 'nextcloud-link/helpers'