Add bookingClass to flight schema

[BigDataKatha]

Add new property "bookingClass" to flight_base schema to allow customers to get very granular with custom pricing widgets and filters for fare class and booking class. We can allow tenants to map the fareClassInput and/or bookingClass to the fareClass they prefer.

https://github.com/EveryMundo/emDataStandards/blob/24b11e7eee3d5753a7bf8ba8051bd4b77be4e7f6/types/flight_base.schema.json#L21

"bookingClass": {
        "description": "One-letter code for booking class given by airline",
        "type": "string",
        "example": "B"
      },

@yartiles @howardem @anahiem @danielsan @neilgoldman @AVivero @renecairo @madhura-everymundo

Please review if we can start collect this new variable.

Note:

• Booking codes were defined by IATA, but airlines have deviated from the IATA standard and current booking codes are airline-specific. Nevertheless, certain booking codes have retained the same meaning across most airlines.

[BigDataKatha]

@anaiscorinne and I decided that we will start collecting the bookingClass. I will update the documentation.

[BigDataKatha]

What we have so far in the emDataStandards:

"fareClassInput": {
        "description": "Name of the fare class given by airline in sentence case, e.g. Economy Basic",
        "type": "string",
        "example": "Economy Basic"
      },
"brandedFareClass": {
        "description": "Standardized fare class name based on the fareClassInput, e.g. ECONOMY_1, ECONOMY_2, ECONOMY_3, MIXED_CABIN_ECONOMY, BUSINESS_1, BUSINESS_2, MIXED_CABIN_BUSINESS, FIRST_1, MIXED_CABIN_FIRST",
        "type": "string",
        "example": "MIXED_CABIN_ECONOMY"
      },
"fareClass": {
        "description": "fareClass mapped to either 'ECONOMY', 'BUSINESS' or 'FIRST' class",
        "type": "string",
        "example": "ECONOMY"
      },
"bookingClass": {
        "description": "One-letter code for booking class given by airline",
        "type": "string",
        "example": "B"
      }

How the industry defines fare class vs. cabin class vs. booking class:

• The cabin class is the class of service you can expect on the plane, whether first, business, or economy.
• The booking class is a letter in a hierarchy, and multiple booking classes are available in each cabin. Each booking class must be paired with a published fare that contains the rules for how you may travel between cities and the price of the ticket.
• The fare class is usually used as a synonym for booking class (see AA, UA, DL).

Therefore, when there is a chance, we should change fareClass to cabinClass.