Invoice tax lines

### Is there an existing feature request for this?

- [X] I have searched the existing issues

### Describe the Feature

I would like this to pull through the tables needed for invoice tax lines. I believe the required tables would be invoice_tax_line, tax_rate, and tax_agency. These are available in the base Fivetran QB connector, but are not pulled through into this flow.

In my QB, these are used to drive a tax payables line on the balance sheet. The addition of these tables is a pre-requisite to additional downstream changes to bring those calculations into the data pipeline. Without these changes the balance sheet and cash flow statement is off.

### Describe alternatives you've considered

n.a.

### Are you interested in contributing this feature?

- [X] Yes.
- [ ] Yes, but I will need assistance and will schedule time during your [office hours](https://calendly.com/fivetran-solutions-team/fivetran-solutions-team-office-hours) for guidance.
- [ ] No.

### Anything else?

_No response_

Start by tracing how the base Fivetran QuickBooks connector exposes invoice_tax_line, tax_rate, and tax_agency, then compare those entry points with the current dbt QuickBooks flow. Done means the three tables are available to the flow and their downstream balance-sheet and cash-flow requirements are clarified; the issue does not name specific files or tests.

Written by the indexing model from the issue text.