Improve eager loading efficiency from `O(n*m)` to `O(m) + O(n*log(m))` (not including the `in_array` improvement)
Improve eager loading efficiency from `O(n*m)` to `O(m) + O(n*log(m))` (not including the `in_array` improvement)

fetch/php-activerecord,shmax/php-activerecord,jpfuentes2/php-activerecord