Resolve "Suggest correct column ordering for new tables (Part II)"

Context:

This Merge Request aims to create a class that receives multiple columns with data types as arguments and suggests the best column order.

I am trying to automate the algorithm defined here: https://docs.gitlab.com/ee/development/database/ordering_table_columns.html#ordering-table-columns-in-postgresql

Class API Example:

columns = [ ['id', 'integer'], ['target_type', 'varchar'], ['created_at', 'timestamp'] ]

new_table = NewTable.new(columns)

if new_table.is_column_order_optimized?
  columns
else
  new_table.optimize_column_order
end

Part I MR: !115 (merged)

Closes #81 (closed)