Fix Travel Invoicing accounting integration

[blimpich]

We've neglected to test this so far in our test workspace. It currently doesn't work, and it needs to work in 2 ways.

1. We need to export/sync settlement transactions. These are when we charge a domain for their travel spend that they owe us. If someone is on a monthly schedule, this only happens once a month. These are not reports, and they are exported differently than the second thing on this list.
2. We need to export/sync individual trip transactions. Every time someone books a flight/hotel/car/train that creates a transaction and normally that would get exported to our accounting integrations as a single line item (I think, the report might be a single line item, not clear to me)

We need to solve both of these issues, but the priority is the first one followed by the second.

[blimpich]

cc: @allgandalf @ishpaul777 in case you have time to look into this.

[blimpich]

Opened up a thread here in slack to talk about this: https://expensify.slack.com/archives/C05S5EV2JTX/p1775250392558559

[rlinoz]

Not overdue, ongoing discussion.

[blimpich]

Investigate: does travel invoicing sync with accounting connections?

The answer: no, no it doesn't. And the fix does not appear to be simple 😢.

I'm going to change the title for this and create 2 sub-issues so we can track this better.

[allgandalf]

Feel free to assign me to the issues, would love to help with this issue

[blimpich]

We're still working on defining exactly what the solution should be here. Once we have a good grip on that we will probably be able to delegate this.