Fallback to scraping users profile page directly for entity_id

[mobeigi]

Add a fall back method: scraping a users profile page directly in get_entity_id_from_vanity_name if we fail to use composer query search.

Which is probably what tools like this do: https://findmyfbid.com/

So far I haven't run into a case where current solution fails though.

[mobeigi]

This or another solution might be required as it looks like ajax/mercury/composer_query.php gets rate limited after some time. However, I was hitting it pretty hard frequently to running script once per day as intended will probably not trigger any rate limiting.

The 'rate limiting' is odd in that the endpoint returns values for some queries (direct friend names like John Citizen but not for vanity name searches / page name searches etc.