Feat/support licensee transaction fees

[landonshumway-ia]

Several compacts have determined to charge credit card transaction fees to licensees, in order to absorb the costs of the fees charged by their Merchant Service Providers. This adds the needed compact configuration fields which compacts will need to specify when they onboard into the compact connect system.

Requirements List

• This change is backwards compatible, as these are optional fields that a compact may or may not choose to specify.

Description List

• Added a transactionFeeConfiguration field to the compact configuration schema, which includes config for licensee transaction fees.
• Returning these values in the API when the frontend gets the list of compact configuration.
• Updated the privilege purchase flow to include these transaction fee charges in a separate line item.

Testing List

• For API configuration changes: CDK tests added/updated in backend/compact-connect/tests/unit/test_api.py
• uint tests to verify licensee transaction fees are added
• Code review

Closes #502

[jusdino]

Looks great! Only one very minor nit, that I won't hold this up for:

[jusdino]

@jlkravitz, this is ready for you!

[jlkravitz]

One nit but otherwise looks great!

[jlkravitz]

@isabeleliassen Good to merge when tests pass.