Function addPlatformFeesToCostSchedule

Add the platform fee to each schedule item using an incremental algorithm.

Algorithm rules:

• The minimum platform fee is $200 USD
• There is an additional take applied to schedule items where the number of travelers is greater than the minimum spots
• The initial additional take is 10% of the difference between the previous schedule items and the current schedule item + the previous platform fee
• Each additional pax increases our "additional take" 1.5% - e.g. If min pax is 9, 10 pax is 11.5%; 11 pax is 13%
• In most cases, the platform fee will go up after each iteration, but in some cases it may go down, but never below the default platform fee