In Hungary, we are already sending invoices to NAV(hungarian tax authority).
Now this module `l10n_hu_edi_receive` provides functionality of receiving vendor
bills through its API and also adds XML importer for Hungarian localization.

A button `Sync with NAV` is added in vendor bills list view, which opens a
wizard where you can select time period and all bills uploaded between that time
are fetched from NAV's API.

Also directly uploading XML is also supported in the format NAV supports.

Flow:-
- After selection of time range, we call `queryInvoiceDigest` endpoint with that
range and it returns a list of digests(consider each digest as separate invoice)
but this digests contains only meta data not all details.
- Now for each digest we call `queryInvoiceData` endpoint which returns xml
response with `QueryInvoiceDataResponse` as root node. This xml contains some
meta data and `InvoiceData` node which has a base64 string, when we decode that
string we get an xml with `InvoiceData` as root node and this xml contains all
details of the invoice, we parse both these details and create bills and refunds.

Also xml importer supports any of the `InvoiceData` or `QueryInvoiceDataResponse`
xml.

NAV Documentation: https://onlineszamla.nav.gov.hu/files/container/download/2025.10.09.%20EN_Online%20Invoice%20System%203.0%20Interface%20Specification%20.pdf

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